Yes, the character's description says:



http://fallout.wikia.com/wiki/Martin

Although it's never been clear whether "it" refers to England or to the company.

So is there any truth to the whole "British Isles Sinking" or just one of those many "wrong" bits of "Tactics"?

As I said, the text isn't very clear on whether the "it" that sank is the company or England, so it's not even certain if England sinking is true in the context of Tactics alone. Even if it is, it doesn't mean that the whole British Isles sank - England is somewhat lower than Scotland, isn't it? And even if it does, we don't know whether this bit is considered canon anyway.

Actually what did happen to Asia, yes I know a bit parts but I'm more refering to India, somehow the second largest country of asia (not counting Russia), did India also get invaded by the Chinese, since that is a damn hard job If you ask me, or is India still in the hands of Great Brittain, wich also would be a damn hard job. ... And I'f we come to India, what about Pakistan ?

Unknown. As I said, the devs purposefully avoided mentioning too much about the world, so that they're not constrained in future games.

That was clearly just a bit of humorous flavor text and not canon. England cannot sink, it's not floating you know!!!! I guess the sea level could rise substantially but that would result in a lot of the world also being underwater.

I know that most real-life nuclear warfare simulations leave Australia, Oceania, most of Africa and South America unharmed by actual bombing, since they don't have their own nuclear armament, and are not considered major threats.

I know that Fallout shows nuclear weaponry in a much more positive attitude, but I'd say alot of these countries/continents would still persist in not having a nuclear program. At the very least, I'd say Oceania, especially the Pacific Islands, would survive. At most, I'd say Australia would survive (It's already nearing its theorized maximum self-sufficient population, which is too small to support a nuclear program), as well as Africa, the southern half of South America, and areas of Africa, as well as Oceania.

NOTE: I'm counting New Zealand as part of the Australian continent.

Do not forgot the fall out universe did diverse from our reality back in the fifties, in our world many countries might not have nukes laying around in that universe it probaly was lots of different and many countries who could afford it did have nukes laying around

Considering Australia is where a heck of a lot of uranium for said nukes comes from, and was the site of the UK testing sites, in a falloutesque world where START and SALT didnt happen, I can see Australia getting nukes... Back then they wanted them, but the UK and the US rightly didnt trust them with nuclear secrets (Australia was known to leak live a sieve at the time - I've heard that the Russians wouldnt bother getting Uk cabinet papers in London, it was easier to get them out of Canberra (ASIO, the counterinteligence department, is still a bit of a local joke there).... Sure its harder, but a homegrown nuclear program is definately possible, Australia has everything it needs to do it.

If instead the US and the UK looked to a big splotch of desert near the new threat (China) to hold a few forward bases (like the US had in Europe to curtail the USSR), those simulations would also look different.

The Fallout Lore states the bombs triggered many fault lines, which caused mountains to rise and whole lands to be drowned by the oceans. So parts or all of England could very well be underwater in the Fallout Universe..

AS of today, there are enough nuclear bombs to completely destroy life on earth 52 times. Look it up.

Conservative speculated warheads as of 2002...

United States 5,535
Russia (former Soviet Union) 8,800
United Kingdom >200
France <350
People's Republic of China 160-400
India 100-140
Pakistan 60
North Korea 0-10
Israel 100-200

That's more than enough!