I've done/still do both gliding and powered flying. I really enjoy the both of them for different reasons. I get more of an adrenalin rush out of gliding, but powered flying is where my heart truly lies.
I started gliding as an initial way into flying, I was about your age and could not afford flying lessons in powered aircraft. I got a scholarship to start gliding (offered by the Royal Aeronautical Society, not sure if they are still doing them or not, might be worth a look though). I soloed in the glider and 16, and what I learned helped massively when I did start my PPL, I sailed through the first few lessons on basic aircraft control, because there are a lot of similarities.
Gliding is a great way to start off in a flying hobby (or even career if you want to head down that road), it's way cheaper than powered flying and there are a lot of skills you learn that you can take across.
Feel free to PM me if you want to anything specific about gliding, or my own personal experiences.