I'm already in Air Cadets, but you don't learn to fly towards your PPL. I've been flying twice for half an hour each in a Grob Tutor.
You need to read up on the gliding and flying scholarships available to those in Air Cadets. Just because you don't know about them, doesn't mean they aren't there
I may have had one or two (ish) hours paid for by HMG via air cadets