This is probably unhelpful but if you actually want to be a film director, a degree in Film Directing will get you no where. You'd be better not going to uni and getting out there and apprenticing yourself to some directors, working as a runner on sets etc. Or going to uni and doing something to do with Scripts and Plays so that you can hone your skills in appreciating scripts and getting artistic vision from them...
If you want to go to uni in America I believe you also need to do SATs - they are tricky and you have toi pay to do them. You'll need these on top of your A Levels.
On the plus side, many of them will offer good grants which can help you get out there.