Pilot16,
Where do you live, exactly? You could certainly give
White Waltham a call - they often hire kids your age part time to help with cleaning aircraft, moving aircraft in and out of hangars, refuelling, and so on. Not too difficult to get to by train from Paddington. They also give staff discounts for flying. I'd imagine that most other airfields would be similar - find any that you think you'd be able to get to, and give them all a call. Good luck!
FFF
--------------