Matt, are you going to FINANCE your nephew's flying???????
The "Odd One" has the best suggestion. Lets see if he has enough ambition to go for the degree, as at High Wycombe.
Actually, he is a bit late in getting experience. Our youngsters at my gliding club (here she goes again, suggesting gliding as the best way to begin learning to fly) begin at age 13 and if they sustain their interest, can go solo at 14.
I watched a lad of 14 last weekend do the entire flight - winch launch, circuit planning, and a first rate landing....his mother saw him do it and she was VERY VERY IMPRESSED.
Before being sent solo, any glider pilot must have experienced and DEALT WITH stalls, spins, launch failures, and circuit planning. And if conditions permit, soaring...
Even if they don't learn to soar, they get plenty of practice doing takeoffs and landings.