Littleflyer
Lots of good advice here, and here's my 2 pence worth, as a teacher, headteacher, pilot and ex-mil aircrew:
Get the most of the very best broad education that you can.
Get Maths, English and Physics GCSE at the highest level you can- As are 10 a penny, so be in that club if you can. If you can afford to fly, you can buy tuition! These skills will serve you all your life.
Get university admission- you can defer if the flying goes well. You don't need a degree to fly, but it's increasingly needed for employment if you don't end up as a pilot.
DO NOT join the military unless it is the thing you really want. You'll regret it.
Finally, don't do the boy thing- "I'm gonna play for Man U, so school stuff is no use to me".
Good Luck
CG