Pilot 16,
I don't know the airports around London too well. I'd take FFF's advice.
Before commiting an awful lot of money and effort to an aviation career. I'd do a trial lesson or something just to see if you like it. My apologies if you have already done this. This way you'll also find an airfield that you can get to. Grab a magazine and see where the clubs and so forth are.
good luck.