Hi Marie,
not sure if they changed it this year but I've been to this since the year it started running. The oldest participant is usually around 16. Its called junior paddlefest because its just for juniors I think! I was always at is as an instructor rather than a participant... They run some courses for adults but they're usually introductory style sessions.
I'd say I'll head down as an instructor this year and afaik you dont have to have a qualification to instruct for the weekend so you could get a few heads together for that, but as far as participating goes I think this one is for the kiddies!