I have given up the opportunity of going to a good university in order to go for this as early as possible...
That's a very big gamble at this time. Your chances of getting to Cranwell in your desired branch are much, much longer than your chances of getting a place at university. Apply for university, and RAF, and then decide.
Or join the RN as aircrew and get a degree while you train:
http://www.royal-navy.mod.uk/server/...changeNav/3533