OP,
Do not let it dishearten you. Why not give OASC a bash? That way if things go well you are on the UAS regardless and if they don't; well you'll have something to go on for your second attempt nearer to the end of your degree and if by that time you are on the UAS you will get a lot of help and advice and you can miss out the AFCO bit as well. The aptitude testing rules have recently changed (no longer 2 attempts but as many as like given that you are under tha age limit and they are sat a year apart. UAS studes can even go down for the weekend to just do aptitude, so don't worry about using up your '2 lives')
Crack on with extra-curricular clubs; drop the Air Cadet stuff (I know for a fact that those that can't move on from the ATC do struggle and get a lot of banter.... we had one who was still doing LL duties and on the UAS!)
You may also want to think up some good answers because I have a feeling the degree may have been a sway there especially if you are uber keen on flying; they'll put 2 and 2 together and think you're after a cheap PPL which is why I think the bursary route may be a good idea as others have quite rightly suggested.
May I ask, which UAS was it? PM me the answer if you want. Good luck, at least you can do English good and proper like
And you have the motivation. I'm sure TPD will be along shortly to show you how much motivation can do for you WRT the UAS/RAF. Also why not hop over to thestudentroom.co.uk and then find the Armed Forces forum? Massive UAS thread over there etc.