Moving to London? Watch
A big difference (I think) might be that the education system here is a bit more advanced that in America so you might have catching up to do, which may be tricky... that's if what I've heard is true at least.
Playing Football, most sixth forms will have a girl's team. If not, you won't be able to play on a boy's team, I think that's against one of the silly rules which the Football association of this country sets. :s