I just thought that you might like to look at this reply which I saw on the Oxford website from one of the instructors in response to a student asking much the same question.
"The best advice on what you need to join the RAF would have to come from your local RAF Careers Office. There's one in virtually every big town. A lot of us at Oxford are ex-RAF, but are probably a bit out of date. Go to the horse's mouth.
However, in general terms, although the recruiting office may only quote the minimum qualifications, in practice, very few get taken on who do not have a good degree, have demonstrated a proven interest in flying and in the RAF, and are, broadly, a cut above the average. That should not put you off from trying - indeed, far from it, if you're the right sort of guy.
There is no problem at all about going from the RAF into a career as an airline, or other sort of commercial, pilot - you will be welcomed with open arms, because it is generally recognised throughout the industry that you will have an outstanding pedigree. The training is brilliant.
The problem will be getting into the RAF as a pilot. They can afford to be very picky at present. They only want the best. And the biggest single thing they are looking for is motivation and commitment. If you are only interested in joining them because it is a cheap way of getting a pilot's licence, they will spot that a mile off - they've seen it all before. The bottom line is - if the circumstances call for it - you have to be prepared to fight and die for your country. Most of us don't very often get called upon to do it - but it could happen. Several of my friends have been killed in flying accidents and minor wars. Are you really prepared to do that?
The RAF is not a job - it's a way of life. You have to be prepared to make that commitment. If you are, you will love it. But if you've only just thought of it because the alternative routes to a frozen ATPL and a career as a airline pilot are too expensive, then you're probably the wrong sort of guy.
I'm not trying to put you off. I was an RAF officer for 29 years. I just want you to go into it with your eyes open.
Best of luck, whatever you decide to do,"