See if you can help out at your local airfield, unpaid at first and then maybe for some small remuneration once you are 16 (many companies insurance will not let them employ people under 16). Even if its just cleaning aircraft, answering the phone, refuelling etc. If you are responsible then and trustworthy then they will encourage you and probably let you have some free flights etc. It will also give you a chance to find out more about flying and where your interest lies.
Doing well at GCSEs and A levels cannot do any harm either.