West ham moved in 2016 from their home
for 112 years Upton Park (aka the Boleyn Ground) to the redeveloped 2012 Olympic Stadium, now
known as the London Stadium.
Getting to the ground
There are basically two ways to get to the ground from Kings Cross. Firstly, you can jump on a tube to Liverpool Street, and change there for the Central Line to Stratford, from where it's getting on for a 15 minute walk to the away turnstiles. There's a tube every 3-4 minutes, and the journey should take you around 20 minutes. It'll cost you £2.40 each way with an Oyster Card or contactless debit/credit card. The cash price is £4.90 each way. The alternative travel option is to catch a fast train from St Pancras to Stratford International. It only takes 7 minutes, but at the same time there are only four trains an hour. The last one that you can catch if you want to be sure of seeing the kick-off is the 16.37. Be aware that the platform is in the "international" part of St Pancras, which is a bit of hike from all the pubs other than Barrel Vault. The fare is £8.20 return, although you get a third off this with a railcard or with a group of three or more. Stratford International is also around 15 minutes from the ground.
If for some reason you choose to drive there then you should be aware that the only parking anywhere near the ground is at the Westfield shopping centre. It'll cost you £9.80 though.
A couple of things you might want to be aware of after the game. The first is that there are reports of groups of West Ham hanging about outside the away section and trying to start things. Also, I've heard that the police may "encourage" any fans who aren't on coaches to march on a circuitous route to Stratford tube station, regardless of where they actually want to go. It may therefore be a good idea to cover up and get your head down, and to try to sneak away from the escort if you're not on the tube.
Virtually all the pubs anywhere near the ground are home fans only. The one exception is the Sportsman, which is pretty close to Stratford tube station. It's a Wetherspoons clone, so the beer and food are good value, exceptionally so for the area. It's possible you may be able to sneak into some of the others if you've got no colours on. If so then three that get good reviews are Tap East, which is right outside Stratford International, and the Crate and Howling Hops. All three have a good selection of cask and craft ales, but all are probably pretty expensive. Alternatively, jump on a tube to either Liverpool Street, where there's a massive Wetherspoons in the station plus numerous other pubs, including the Magpie and Lord Aberconway, close by, or to somewhere like Leyton (where the Leyton Technical is worth checking out).
If you're down on the train you best bet is to either head for Liverpool Street and the aforementioned pubs around there or just to drink around Kings Cross and travel to the ground late on.
Kings Cross pub map
Football Ground Guide
London Stadium matchday guide
Stadium area map