Do i join up after Sixth Form or Uni?Watch
Go to uni.
Don't do an aviation-specific degree, but go to uni if you can. You'll be with people your own age, you can join a UAS / RNR and learn and do relevant stuff, you'll also be getting something that helps you get on in your career (better trained mind) and something to fall back on.
Go to uni.
You'll be taught the military way of doing things rather than them saying 'oh - you have a degree in this, don't bother with our training'. The degree you quoted is not lined up for the career fields you are interested in, so you may as well do a degree that you are already interested in. It would not give you any advantage in a military career.
Don't choose a degree solely on potential career prospects, choose one you enjoy and will excel at.
Posted from TSR Mobile
As with many other career fields, senior management are more commonly undertaking Masters degrees - be they MBA or other topics - as part of their personal and professional development. Without having that degree as a foundation it would be very difficult indeed to put yourself along side those with the higher qualifications.
Going to uni and getting a degree is worth far more than the money you would make if you did manage to join at 18 or 19.