Warning. Great Wall Of Text ahead.
So you've decided to head across the Pond to London for the two game series at the end of June. You're an absolute legend, following your team across an ocean, and we should have a suitcase statue in Monument Park for dedicated people like your good self.
The only problem is, you don't know what you're going to do with yourself. Maybe you already have a game ticket, maybe you're hoping to snag one outside the stadium in the Stratford area of London, maybe you just want to visit London and having the Yankees there gives you an excuse to check things out. But all you have right now is a vague notion that you want to make a memory of a lifetime and the clock is ticking.
You don't want to stick out like a newbie. Thankfully, you've got an old pro helping you out. Fifteen years working on the railway, including working at Kings Cross and St. Pancras stations, and a thorough love of finding out the best way to do anything quick and cheap and easy. Jackpot777 at your service with a brain full of London.
I've broken this down into sections with bold headers. Look for what you need to know, get prepped, get excited… let's shag it, people. Oh, and I'm using a hotel that one person is actually staying at as my examples. Thanks to Fantasysage for that. I already gave him four musical things to find in his own area, four pieces of musical rock & roll history that would take just a short afternoon to do, but if you're near Leicester Square / Piccadilly Circus / Oxford Street and you love music you can check out those yourself too by reading this from my announcement thread.
Yada yada yada, here we go. And apologies for mentioning the iPhone a lot, the examples I'm giving use it because that's what I have.

Getting over there. What do you mean you're waiting for inspiration?

First off, a saying that'll make it sound like you backpacked around the world since you were two months old and this is the norm for you. The best time to book your tickets was four months ago. The second best time is right now.
As we get closer to the date, the less likely you are of getting a flight on the cheap. Even closer still, you're not likely to get a seat at any price. Get onto Kayak or Travelocity and book the flight. Now. Read this section first, book your flights, then come back and read the rest. You're flying to London in summer, you're coming back to America around the 4th of July when SO MANY PEOPLE plan to come back, so if you can go for ten days and return when most of the firework displays and family shindigs are happening you'll save an absolute packet.
Airport time.
If you're able to go from JFK (you may have noticed that every passenger airport in the world has a three letter code), those are probably the cheapest flights. London to JFK is like a cheap pipeline with airlines competing for your money. After that, flights are relatively cheap from Newark (EWR). All those flights will get you either to Heathrow (LHR) which is technically within the London Zones area or London Gatwick (LGW) which is just south (more on those Zones in the TfL section). Right now, round trip flights are around $600 but prices might even creep up if enough of you keep searching for the same dates and same routes. It's all supply and demand, so searching can raise the price. Be wary of that.
If you're in upstate New York or you're a RailRiders fan in the Scranton area, one cheap option is to fly from Stewart (SWF) with a connecting flight at Dublin to London Stansted (STN) which is east of London or London Luton (LTN) which is north of London. That will cost a little more than the previous options, but it's a lot cheaper than flying out of Wilkes-Barre Scranton (AVP) and changing at Detroit or Charlotte or Philly. Drive up I-84 as if you're going to Poughkeepsie for 90 minutes and you're there.
Think of those outside-of-London-Zones airports as being like Newark, by the way. Technically not in the city, not even in the same county, but a short ride on public transport to the middle of everything.
If you can wiggle your departure and return dates, especially because there are going to be a LOT of people wanting to visit family for the 4th or (more probably) the Saturday after when all the fireworks displays are, I heartily recommend it. Use the functions on the websites to compare prices and book accordingly. Here's an example from Kayak of a RailRiders / Yankees fan going on that flight via Dublin and then arriving in either the county of Essex or Bedfordshire (Stansted and Luton airports respectively) and coming back around the 4th. It's actually cheaper to fly back ON the 4th because most people don't want to split the actual holiday with a day of travel. And coming back to surprise the family on the 6th is where the dollars pile up. The tools are available on the travel booking sites. Use them. Figure out of staying an extra day actually saves more than you'd earn working.
OK. You got your flight. Now you want to think about a hotel room or something. Where in London should you stay?
This is a very simplified Tube (the subway system is called the London Underground but locals all call it The Tube) map of central London. There are also above-ground trains run by rail companies, and bus routes, but I'm keeping it simple here. The more astute of you might notice there's a shape to central London that looks like a milk or stubby beer bottle on its side with the yellow line. When the games happen, the stadium is going to be a bit further off to the right of this map, so if you want to still be in the middle of things for the touristy stuff but still have a short-ish journey time to the London Stadium, I recommend staying to the middle or right hand side of this milk bottle based on what your nearest Tube station is.
A more complex version: the British equivalent to Zip Code +4 (the bit across the Gerard Avenue from Yankee Stadium is in the Bronx area of 10452, and the offices at 901 Gerard Avenue are 10452-9992) is called a post code. With the London Stadium, site of the two games, the post code area is E20 (for East London region 20) and the part of "East 20" that has the stadium is 2ST, so their version of the Zip+4 is E20 2ST. Just as with 10452-9992 where the important part is the 10452 bit, the important bit of E20 2ST is the E20 bit. London East postal district 20. So you want to be more in the east than the west, and E20 is in the north part of east London so north of the River Thames is preferable to south. Anywhere with a Central (EC or WC number) is still good. Other places outside of London get postcodes based on a nearby big city (like LS for Leeds of M for Manchester) or the nearest large town (LU for Luton Airport because Luton's the biggest town in the area or CM for Stansted because Chelmsford is the big nearby urban area) but London is big like New York so it gets North and West Central and -- you know what? I'm getting sidetracked. With London post codes, east rather than west and north rather than south for accommodation.
In Fantasysage's case, he's staying in a hotel in W1. Didn't I say east rather than west? I did, but his area of W1D (West 1 D) is right on the border, two minute walk away, from WC2H (West Central 2 H). He got a great deal in Soho just north of Chinatown, close to the lights of Piccadilly Circus (it's like Times Square, there's even an M&M Store nearby but don't go to London just to visit that) in a hotel with great review scores. NW1, W1, and SW1 postcodes are good areas because they're basically joined to the Central codes.
And yes, like with the 212 area code and Zip Code snobbery here, the same thing exists in London too. East End boys and West End girls, as the Pet Shop Boys once sang about. It's good to know a bit about that so you stay in a good area, just like any big city.
This is a lot and we've only just got the flight and hotel room booked. Now what?

Prepare to hit the ground running before you get there. Your smartphone helps SO much (even with no connection)

You probably know that your Verizon or AT&T plan isn't going to just transpose over to a UK network. AT&T has a deal where you can pay $10 a day to use your phone in London, and you're only charged for the day you use it like a traditional cellphone for example, but be aware that your data limit per month is still the same. Personally, I like traveling over there and leaving my iPhone in Airplane Mode so it doesn't ping cellphone towers and you don't inadvertently run up a horrendous bill. What good is that? Well, like in any big city, there's free WiFi all over the place. Fast food places or Starbucks, in your hotel room, some areas of London provide free connection like the N1C area of Kings Cross because Google have an office there (so that means anywhere with a postcode beginning with N1C just became very desirable). There are black phone boxes that are hotspots.
You can arrange to communicate via Facebook Messenger or Skype or iMessage and FaceTime (video or just audio) on an Apple device. If there's some reason for you to remain connected with someone back in the US of A, agree on the method, download the relevant apps, and try it out before you travel to make sure it works for you.
Some people swear by getting a region-specific pre-paid SIM card and popping that in the phone for their stay. It's cheaper than the AT&T option I mentioned earlier: an O2 provider card giving 8GB of data with 2,000 talk minutes and 5,000 texts for a whole month costs less than $30 and you don't have to worry about looking for a WiFi signal. But, like your mother says, put the WiFi on when you get home so you're not eating up all that data watching Fortnite flossing videos or whatever it is you kids do. Get off my lawn.
Apps. By the GODS, there are some great ones. The best one I can recommend is CityMapper for Apple or Android. Every decent travel website and YouTube travel video urges you to get it, and I agree. I used it in London and Paris last year, planned journeys before I got there, and if you're connected to WiFi or decided to connect with the SIM card you bought it'll update travel info in real time.
If you use Google Maps, you can download areas and access them offline. I still have a HUGE area of London saved on my phone and it takes up less than 100MB of space because it's just vectors, just colored lines and a font or two. You don't need a cellphone signal to use them because your phone navigates via orbiting GPS satellites and that uses 0% of your data or cellphone signal. And like any Google map, you can pinch and zoom and search in that area as if you were online.
Also remember that you can store PDFs and other documents on your phone. If you save a PDF map of the entire Tube system, an iPhone puts it in your iBooks. You can store all types of maps that can be enlarged for details in there. In fact, here's a link to one of those maps now. Save it to your iBooks or whatever the other phone equivalents are.
Just take another look at that bigger map. You can still see the milk bottle on its side in the middle, in Zone 1. And you can see the other Zones spreading out like concentric ripples. The Tube lines are color coordinated: the Central Line is always red, the Northern Line is always black, the Piccadilly is always dark blue and the Victoria is light blue.
Now would be a good time to start with how to get around.

Transport for London. That's what TfL stands for.

IMPORTANT NOTE ABOUT ANY AIRPORT EXPRESS TRAIN OPTION. You may see the Gatwick Express can get you to London Victoria in 30 minutes, or the Heathrow Express can get you to London Paddington in 15 minutes or 20 minutes if it’s Terminal 5. And they can. But unless you are specifically going from that airport and your nearest station to your accommodation is the relevant London location, these options are a waste of money. A journey from Heathrow Terminal 5 to Green Park by conventional Underground takes 50 minutes and costs under £15 for that and all your other public transport for the day. The same journey involving the super fast train to Paddington and then changing for the Bakerloo (Brown) and Jubilee (Silver) lines takes two minutes longer and just the Heathrow Express part alone costs £22.00.
You may think about getting a cab from Heathrow to your hotel. It’s £65 one way, almost $85. Don’t be a dozy pillock, that’s the kind of money you could be spending on beer.
You may be thinking of a hire car for the week. Don’t be an even more dozy pillock. Cost of fuel? Parking? Steering wheel on the other side of the car? All the other cars on the other side of your car? Road signs you don’t understand? Road markings that mean you’re not allowed to pull into this intersection, do you know what they look like? Rush hour in a city with nine million residents and millions more commuting in and out, plus a few million more tourists? Good luck with that idea, you’re having a laugh mate. Stick to the buses and tube and trains.
WHEN USING THE ESCALATORS, ALWAYS STAND TO THE RIGHT AND WALK ON THE LEFT. One station tried changing the system for six months in 2016. It nearly led to an overthrow of society as we know it. When someone comes out of their own Personal Tube Bubble to call something a “fresh hell”, you know the system has failed! The experiment was scrapped because, and I am not making this up, it “goes against everything about being British”. Someone else said it went against etiquette and “there was always the danger of people thinking they could stand on the left at other Tube stations - can you imagine?” which is possibly the most British thing I’ve ever heard.
You have all your travel pre-paid before you even fly out, if you have one of the following:

• one of those newer contactless credit cards that Saquon Barkley keeps getting fooled into using.
  
• ApplePay connecting your iPhone or Apple Watch to your regular US credit card.
  
• Samsung Pay, or Google Pay. Check out the list here of phone pay methods accepted.
  

This is because Transport for London (TfL) has been rolling out contactless pay for seven years now. Buses in late 2012, and the rest of the network in 2014. All these things contain a standard type of chip that deals with the payments.
HOWEVER - some people reported problems with trying to use a non-UK card payment to jaunt around. There is a card you can get specially as a travel smartcard. It's called the Oyster Card and there are two types. You can either buy one when you get to London, it's the standard blue one… but I recommend getting the one only Visitors from other nations can get, the Visitor Oyster Card. It makes for a nice souvenir, and you can pay for it with an amount preloaded onto it. That way, you arrive in London and head straight for the public transport, press the card on the sensor and it starts deducting your fares. And there are a few perks with the Visitor version …for example, if you spend £5 ($6.50) in the Beatles Store near Baker Street tube station and show a Visitor Oyster Card, you get a free gift. 15% off your purchase at M&M World. Alright. I give in. Go to the M&M store for half an hour. Treat yo self.
Currency. Forgot about currency. One pound, £1, will cost you around $1.30 or so. The exchange rate fluctuates but right now it's around that. Something costs £10, that's around $13. A Big Mac in a McDonalds (if you must) is £2.69 (that's $3.49, which is actually cheaper than what it costs over here). Something £10 is $13, £50 is $65. Add a third on top to any British price to get a close conversion to how much that is in dollars. And there's very little tipping for service, it's a cultural difference. Visa and MasterCard are accepted everywhere too, but call your card issuer on their number on the back of your card to tell them when you’ll be in London. That way your account won’t be frozen for suspicious transactions when you’re 3,500 miles from home. ApplePay and SamsungPay and GooglePay too because they use the same chips as the cards and it all links back to Visa and MasterCard anyway... those contactless payment terminals are everywhere. I paid for a pub meal in Hertfordshire (just north of London) last year using my iPhone 8 because I have my LLBean Visa card stored as a method of payment. Used it to buy pre-packed sandwiches and a bottle of water at a pharmacy (Boots Pharmacy, the UK version of CVS).
Just don’t expect anyone to take dollars. Any shop that does will give a lousy rate of return. Get maybe £150 in cash for the week for small transactions like buying beers but do most stuff on credit card. Payment protected, and you get the best rate of return. If you have to exchange dollar bills into Pound banknotes and coins over there, go into a high street bank or building society (they’re a little like credit unions, you could say) and ask if they exchange foreign currencies. The exchange rate is better than at a street “Bureau de Change”.
ATMs are everywhere. The locals call them “cash machines” (like the Hard Fi song) or “hole in the wall” (like the eleventh pub’s name in The World’s End). Your bank may charge an additional fee or you may have an account that waives ATM transaction fees worldwide. Ask at your local bank.
That’s money dealt with.
Back to travel. Going back to that large map, and see London and its Zones. Most of the tourist stuff are in Zones 1 and 2. The stadium is near Stratford and Stratford International stations to the east (E20, remember) in Zone 3 and is served by above ground trains and the Central (red) line of the Tube. Heathrow is in Zone 6 on that dark blue (Piccadilly) line to the bottom left in South West London. Gatwick is out of the Zones and is mentioned at the bottom of the map.
When you travel, there is a maximum you will be charged. Once you reach that Daily Cap, every trip after that is effectively free. And the price depends on what Zones you use. The further you travel, the larger the cap for that day. This man suggests buying the Oyster Card in London. You don’t get the shopping perks but you can surrender the hardware on a standard card at the end of your trip and get the £5 fee back, and maybe just load £15 onto it for the first day and then top it up on a regular basis during your stay. And as you see, everyone stares at their phones and has earphones in too. If you do that, you can check your travel plans on your smartphone screen and nobody needs to know you’re a tourist.
If you travel via Heathrow Airport in Zone 6 into the middle of the sideways milk bottle in Zone 1, the most you can charged for that day, Zone 1 to Zone 6, is £12.80.
So let's imagine that day you arrive. You arrive early on a weekday morning on that red eye flight from JFK and start travel before 0930 because you got a flight arriving dead early, and you take the Piccadilly Line regular tube service and get off at Piccadilly Circus station so that's £5.10 charged (your hotel is in the middle of Piccadilly Circus, Leicester Square, and Oxford Circus and the app said that's the shortest walking route). Get to your hotel and they say you can check in before the usual 2pm (or whatever) check in time because there is a room already cleaned that wasn't used last night, and it still feels like six in the morning to you even though it's 11am local time so you set an alarm for 2 hours and grab a quick sleep. Wake up, shower, change of clothing, you connect to the hotel WiFi and Google map somewhere to eat that involves a short Tube ride. There's a pub called The White Lion, it's two stops further up that same dark blue Piccadilly line at Covent Garden (totally in the middle of that milk bottle) and that English guy that writes novels for tourists on the Yankees subreddit said their fish and chips in their upstairs dining area are good and their beer is decent and cheap enough because the pub is owned by a brewery called Nicholson's and they serve their own product (and you want to try a local beer so that's perfect). That trip cost another £2.40 because it's totally within the middle two zones, so you're up to £7.50. You then travel to Kings Cross (Zone 1) after your lunch and slow beer to visit the Harry Potter store on Platform 9 and three quarters so that's another £2.40 so you're up to £9.90. You heard that Camden Market is the place to check out Doc Marten boots like Vinnie Jones wore in Lock Step & Two Smoking Barrels so off to Camden Town tube stop in Zone 2 for another £2.40 which puts you up to £12.30. You see a London double decker bus going to Euston (your PDF map and the CityMapper app show you that's back in Zone 1) and buses are only £1 so you should be up to £13.30… but this first day is capped at £12.80 so the bus only cost you 50p (50 pence. The subdivision of one pound is one hundred pennies, or one hundred pence). The tube back to Piccadilly Circus or Oxford Street or Leicester Square for the hotel is free because you hit your cap.
Just make sure you tap in on a sensor at the start and the end of any journey involving rails, and on a bus you just need to tap in on the sensor at the start of your journey. Tap in, tap out.
The next day you stay totally within Zones 1 and 2. Palace, Westminster, London Dungeon, Baker Street, but never outside the middle. That day caps out at £7.00 so your third trip on the Tube is discounted and anything after that is free.

Travel to the London Stadium. If you have tickets, it'd be a shame not to use them.

On the day you go to the game, you need to travel to the Stratford area of East London in Zone 3. The daily cap for that day, assuming you don't venture further out into Zone 4 and beyond (effectively residential areas) is £8.20. When you get off at either Stratford (regular rail station or Underground station, they're the same thing) or Stratford International from St Pancras International (the six minute train ride on a Eurostar type train), there'll be lots of people helping the fans. The stadium is an Olympic stadium, it's huge. And everyone will be walking to it. It's like following the crowds up River Street if you've never been to Yankee Stadium. The crowd carries you forward.
The stadium is now the home to Premier League team West Ham United so head for the 55,000 seater stadium that says West Ham United on it. Their colors are claret red / light blue / white and their emblem is a shield with two hammers on it, so their nickname is either “The Hammers” or “Irons”. They used to play at the Boleyn Ground just three miles or so away in East 13 but the opportunity came to move into a new already-built stadium starting in 2017 so they took it because their old place dated back to 1904. The old place was demolished and it’s a park now. A bit like the old Yankee Stadium story ten years ago. Here is what it was like for fans of The Hammers when they went to their first home game at the new stadium in 2017. That’s the experience you’ll have.
So you’ve probably figured out how much to load onto the pre-paid Visitor Oyster Card (which you should order soon so it gets delivered before your trip). £12.80 for the day you arrive. £7.00 for any day just doing tourist stuff in Zones 1 and 2. £8.20 for game day. If you’re only going to Heathrow on the final day, another £5.10 for that single journey. Add up the days based on that, come to a total, and pre-order that amount on the Oyster Card ASAP.
This is all part of the transport info, but what do you do with any small amount of credit left on the card when you get to Heathrow for the flight back home? Well, you can check the remaining balance at any time from a machine at the stations and that machine will also refund a balance up to £10 so don’t put TOO much pre-paid on it. But what if you don’t put enough on it? Well, you can use those same machines to top up the card with a few quid more.
Quid is a slang term for pounds, like bucks is slang for dollars. It’s always quid, never quids. Ten quid is thirteen bucks.

Get me to a bar of likeminded fans. The vaguest section here.

Right now, I don't know of any bars or pubs that have said "we're definitely showing the game, and we want as many Yankees fans to come" but that will change. Keep watching YES to see if they mention a place, keep reading the subreddit in case info makes it here. It will. And that's when you make those plans.
If you’re over there, watch ITV News London or BBC London News.
And if we find out anything, I’ll amend the shit out of this section.

General tourist information and how you know more British stuff than you think.

The same rules apply in London as in New York. People that look like they know where they're going don't get accosted by society's more nefarious people. Anyone that looks fifty years old that steps off a Tube train wearing an NYU sweatshirt and a Giants cap may as well paint a huge target on their back as being a potentially easy target. Tourists don't know the place well, they don't know you have to dial 999 for emergency services instead of 911, they're more likely to be carrying around lots of currency they're not naturally comfortable with and more credit cards than the average punter. This woman will set you right on how to blend in. Blending in is always key.
Don't flash cash and cards around. Don't talk at 95 decibels about how new you are and how confusing everything is and how you're totally lost. Generally: don't be a feckless wanker. Be smart, which means be criminally minded (to borrow a line from KRS-One).
Culturally you'll fit right in. Britain and the States share a lot of media, and a lot of that is centered around London and New York. If you or your wife likes Leona Lewis or Adele or Mumford & Sons or Gorillaz songs, they're from the general London area or have members that are so you know that. If you remember Wonderwall by Oasis or Song 2 by Blur or Common People by Pulp, you basically already know of the Britpop music scene of the '90s (which is a major part of the contemporary British psyche). You may already know some slang from Harry Potter films, you may know a few Bond movies and how Austin Powers makes that stuff comical (and Mike Myers is Canadian), Star Wars has had a British and American influence for over 40 years. You may even be able to carry on lengthy conversations with a Londoner about the best moments in Top Gear, Doctor Who, Monty Python, Game Of Thrones, anything starring Idris Elba… all it is when it comes to being there is the small differences. Steak sauce is brown sauce, a truck is a lorry, pants are trousers and so on. Just look at the small language differences as being like a form of slang.

Some stuff can be weird and unexpected. Some nice, some just weird.

The voltage is different. Make sure you have the travel plugs and adaptors you need for the UK. They're at 220-240 volts, 50 Hertz.
There are free newspapers at stations on weekdays. Metro in the morning, Evening Standard in the afternoon. Grab a copy to keep up with the world. I’m sure Metro will have the Yankees - Red Sox games in it the Monday after the games. Grab a copy as a free souvenir.
Washcloths. My wife reminded me of this. You get the usual assortment of of hand towels and bath towels and floor towels, but enough places haven’t had washcloths (or as the British call them: a flannel) that I’m including it. There is a chance your London hotel doesn’t do washcloths and I don’t know why. Pack a cheap washcloth or a shower poof from the dollar store for the trip and leave it in the shower. Usually, hotels only wash towels you leave on the floor because it’s an ecological thing so hang the washcloth in the shower and you’ll be fine.
Temperatures are in Celsius. Quick rough-and-ready conversion that’s super easy and pretty accurate: take the Celsius number, double it, then add thirty. So if it’s going down to 10°C at night, double it to 20 and add 30 to get 50°F (which is actually correct). If they say the high will be 27°C or 27 degrees, double it to 54 and add 30 to get 84°F (27°C is actually closer to 80°F but it’s close enough for you to know it’s short sleeve weather).
Daylight is longer. London is 52 degrees north of the equator, New York is between 40 and 41 degrees north. The Bronx is closer to the equator than the North Pole, but with London it’s the opposite. That means winter days are shorter but summer days are longer because you’re further north in summer. They have daylight savings time (British Summer Time, BST for short) so the birds start their twilight singing at 3.00am or so. I’m not even joking, if the clocks hadn’t been put forward that shit would be 2am local time. Sunrise is at 4.45am the time you’re there. Sunset is 9.20pm. It won’t get totally dark until around 11pm. Look forward to long summery late evenings. I bet you didn’t think astronomy would be in this guide, but if you’re not ready for songbirds “giving it all that” at three in the morning it could be quite an unexpected shock. I promised you lot a comprehensive guide and that’s what you have.
And try actual British Cadbury’s chocolate. I recommend the Cadbury Flake. You’ve not experienced chocolate until you eat a Flake.
You'll do alright. Wait, I typed HOW MUCH?!?