Thanks for all the replies - as mad_jock knows due to a thread crossover, I currently help with scout gliding, do work for a balloon chase team in return for flights and do Amateur Photography. It's obvious that, while experience and knowledge is important, individuality is also important, and a quality not to be under-estimated in it's value.
I'll keep on looking for openings, as some schemes offer the chance of immediate application for someone my age, with a few British and American schemes not requiring any A-Level grades for application. Meanwhile, time for me to go and get a medical!