..."livin' like a good boy, outta" , sorry, I couldn't help quote the Scissors Sisters line from your subject.
I bet if you move back to the US down the road you'll miss all the great things about the UK. I know there are things I miss from both whenever I'm in the other country!
I'm sure you'll start to get used to life here, obviously, you've just moved over here and you're focusing on the good things from back home to forget about the stress of the move, the smoky roommates, etc. It's great that you've got gfs to hang with, nothing like friends to make things a bit easier with the transition.
You may find not too far down the road that you can get out of the smokey flat and find a new, non-smoking roommate or even move into your own flat. I know how bad the smokiness can get, I lived with 5 other smokers in a flat in college, nice guys, but the smoking bit really stunk (no pun intended).
Matt