If you would like to learn to fly a glider, it is suggested that you should go to any gliding club and have one or more Air Experience Flights. If you like the experience, you should then join the club, where you pay your membership and flying fees, but the actual instruction is free.
Alternatively you can go to a commercial gliding school for an intensive course. This is often a much more expensive method, but students often get to fly solo in one week! Three such commercial organisations are:
It is legally possible for a young person to "solo" at the age of 15 years, and in fact many do! There is no Licence required and the authority to fly a glider is given by a Log Book endorsement by the Instructor.