Capt2010 and others, you might just check out civilian gliding clubs; consult the British Gliding Association website. Visit the ones nearest, talk to people.
To become an instructor because you would like free flying is suspect. First of all, gain experience, gain judgement, fly cross country, visit different sites, experience different conditions. Earn your Silver badge, at very least.
And then when you are a very very safe and experienced pilot, and you love teaching one to one, then begin to consider becoming an instructor.
First things first.