Regarding degree choice and UAS The Student Room is probably a better place to ask the questions.
1) What is your general opinion on doing an aeronautical engineering degree for someone wanting to become an RAF pilot?
As good as any other.
2) Last time I went to the optitians (8 years ago) I was told I was slightly long-sighted (and I mean slightly). Is this bad?
Go back.
3) Does anybody have any experience in the UAS? Is it enjoyable? Is it worthwhile? Is it realistic?
Depends on you. Not a silly answer, btw.
4) I know the RAF aren't recruiting pilots yet, but have they actually released a 'date' from which recruiting will commence? I've seen april '12 and '13 being knocked around.
No, 'they' haven't.