Hey I too like you started my PPL In year 11. I applied for Work experience at my local flying club but my school turned it down because of healh and safety?!
I did however manage to secure a place at Cobham aviation, work that one out.
Anyway i would definitely budget for at-least 7k and the rest as you will probably require another 15 or so hours on top of the minimum 45 unless you are a natural!
Best of luck,
Greg