Jonnypiano,
Im currently on the aeronautical engineering course at Bristol Uni. The course is very hard work, and a lot (if not most) of it is not particularly fun even for someone obsessed with aircraft! With regard to maths, you will need a pretty high standard- i found GCSE pretty easy, Alevel less so, but something like 10-15% of the year have an alevel in further maths at a grade A. many more at a lesser grade. I didnt do further maths (ecept for a couple of extra units) and i stuggled with some of the maths at uni. I'm not saying you need to enjoy maths, just be competent at it. I dont want to put you off is its what you want to do, but dont do it as just a way to an airline job. Many people drop out for this reason. However if you find engineering and aircraft interesting and you can handle the maths then go for it, it is a very rewarding degree, you feel you learn a lot and im sure it wont harm you r career prospects!
Sorry for such a negative response but i thought my viewpoint might be helpful.