Don't sell it, you'll regret it...
Plus, you'll find it cheaper to buy said teenager a cheap runaround and insure that, than putting them on your insurance as a named driver.
If you do sell, 65K miles is relatively low so you could ask for £8K ish, maybe more, for a private sale but expect a lot less from a dealer.
Give Giles at Abbott Racing (tel: 01255 870636) a call, they are on the lookout for good low milage Aero's at the moment.