Generally speaking I tend to oppose too much multi-nationalism when it comes to post apocolyptic concepts. There are a lot of reasons for this. Chief among them is that the world is supposed to be pretty much decimated. It's supposed to be incredible that human life survived in any noteworthy form in the most powerful and well protected nation the world has ever seen. Once you start going global with it you simply wind up with too much civilization surviving to really maintain the atmosphere, and then you've got situations where of course you have differant nations wanting to show that they did better than other ones, combined with the general progression of a series where each new chapter includes new and better stuff than the previous ones, and if you say start adding those things to places that wouldn't logically have them it also causes some problems with world building.
I might not be conveying this right, but to an extent look at say RIFTS by Palladium. The simple realities of ongoing publication and power creep created a situation where you had all of this massive power and uber-mecha and stuff sitting in places like South America or Australia despite what had happened. What's more it got to the point where you could barely look at a map anymore without some massive powerhouse being set up close to pretty much everything and it kind of made the world seem a lot less apocolyptic as as nasty as it was civilization, manufacturing, and uber technology was everywhere. They even wound up having to redo/retcon/update a couple of the groups that were supposed to have been the major powerhouses (like the Coalition) because power creep had made them lulzworthy despite what they were supposed to be. While it would seem on the surface to be a good thing, I found that having people from a given region help write a given region leads to national pride turning things into a much bigger deal than they should be.
To put things into perspective, I'd say that Europe in Fallout would logically be totally decimated. Probably one of the reasons why someone like Mr. Tenpenny considers living in a refurbished skyscrayper such a good thing, and came to America to begin with given the oppertunity. I would say there probably isn't a london, or really anything gamable there. Just boring desperation. Sort of like "The Road" compared to "Mad Max" if even that.
The reason why I say this is that if there was a war with China, Europe is right in between it and the US. For all pretensions to the contrary Europe also has very little in the way of military power at this level. European powers having been sort of proud of their anti-nuke policies and while capable of destroying a few cities they can't blanket the world like other powers. In terms of sheer numbers the europeans also can't put enough boots on the ground to deal with the incoming Chinese. What's more in order to engage the US, they would have to take over Europe and pretty much flatten it just to take out the missle defenses (like the base we have in Poland that was under heavy discussion with the Russians). If Europe was a US Ally it probably got nuked and wiped out by the Chinese, and then nuked again by the US once it fell to try and stop them. If Europe was a Chinese ally, again it probably just got nuked out of existance by the US to again stop the Chinese from using it as a beach-head.
One of the biggest advantages of the US militarily is simply put that we're seperated from everything else by oceans. You have to cover a LOT of the globe just to get to us, and if your coming from the East/Far East you pretty much have to get some strong beachheads in Europe to even have a chance of moving people here in any numbers, or reliably target us with missles or whatever for that matter.
Whether it was Russia (old school), or China (new school), simple placement means nobody is going to remain untouched and neutral even if they wanted to be. Since we're dealing with a situation where the globe is defined as "totally fragged apocolyptic nightmare" pretty much anything that hit the US or China is going to be 10x worse for anyone with the misfortune to have been stuck between the two big guys when they decided to go at it.
The need for oil to fuel war machines and such means that even the old "Farnham's Freehold" arguement made by Heinlan of Africa remaining untouched is unlikely today because simply put everyone would be after the oil in the region, and frankly the region would be doomed to be uber-nuked because no matter who was in the stronger position there, the loser would always wind up making a priority of decimating the region to deny the resources to the enemy.
It's one thing for DC to survive at the level of Fallout 3 (which is admittedly pushing it) given our status as a superpower, AND the general distance from the enemy. While a power England is not a super power, and on top of it it's right in the middle of everything and by the time things went far enough to leave the US and presumably China both in ruins it would have been slammed by both sides one way or another once things went this far. Neither superpower would let the other control Europe (the middle ground) and would totally irradiate it just to prevent it's use as a staging area if they saw a chance of the other side getting a beachhead/maintaining an alliance there.
The bottom line is that I would think that it would be pushing it to put enough stuff in whatever is left of London to give it story potential. Heck, I'd be surprised if London is anything more than a giant crater in the Fallout universe.
Given the science fiction aspects and the fact that China was beint portrayed as a scientific equal to the US on it's own merits from what I've seen so far, I suppose it's possible that even if it was blanketed you could have some civilization surviving in say Beijing or whatever. It wouldn't be any better than what survived in the US I'd imagine,
but it might be similar.
