Yes a back up plan is good.. is this why you are going to uni??
You dont really need uni for the aviation world (Well, thats MY OPINION), A levels yes. Good you got into a grammar school.
If you want to be a commercial pilot as quickly as possible then keep the gliding going, but take it easy on the flying due to the cost.
If you want to join CTC/integrated courses/fte/oxford etc.... they dont give you a refund for having a PPL before. You still have to pay the full course cost (thats what happened with me. Other people may be different)
But if you decide to keep you PPL going, then CONSIDER going modular, and keep your gliding going. The scholarship would look impressive to an employer i would imagine.
In this day and age, it's just how you get your foot in the door with an airline at the moment. Everyone seems to be taking people thorough school directly. There has been no direct employment from the companies for a while (I MEAN FOR NEWBIES)
(apart from Jet 2 in recent months, and they quickly decided they had too many applications and seem to have gone to oxford for the inexperienced guys)
So, do a few searched and have a think. CTC seems to be massive, and easyjets link with them must be a good stepping stone! But then you pay your money and hear some people staying in the pool for years.
Up to you! concentrate on school and deced what to do in a few years during Alevels