Hello,
I am 13 years of age and I have my heart set on being a pilot. I have decided that I am going to join the RAF. But I don't know what qualifications I need to study at school and university etc. Could anyone tell me what opportunities there are available in the RAF and help me to take a step forward? 
Nice to see enthusiasm from a young age! Study what you feel you will enjoy. In the end the RAF want to see enthusiasm and a hard worker, so what ever you chose - be GOOD at it!
Chose A levels during your GCSE's - get a feel for what you want to do then, see what you're best at or enjoy. Uni - you need to decide when you're older to be honest, i never knew when i was 13 that i was even going to end up at uni!!
Whilst at school, get into clubs and take part in after school sports. It will help a) your fitness and b) show you're a team player when at OASC. Same with College and Uni. If you've got a local ATC sqd, get involved, it'll open up opportunities to you that your friends will envy you for
i THOROUGHLY enjoyed it.
In the end, stay honest with what you want to do, stay enthused and get involved
Steve