This should probably go to Wanabees, but since you asked:
You could go to Uni and enjoy yourself and gain a valuable qualification. While there you could join a University Air Squadron and get free flying training from the RAF without needing to commit yourself to joining the RAF afterwards - sounds too good to be true, but it is!
Gaining a flying qualification costs loads, so anything you can get free is worth chasing. You can also apply for a flying scholarship right now with the Armed Forces (contact a recruitment shop) again, no commitment. The Air League also run flying scholarships (I support them, so if you get one - buy me a beer) and other organisations run them as well - the Aeronautical Society? Not sure. Search on the net.
Good luck. You will need bags of determination, no one will hand you it on a plate.. Go get um tiger.