My rather simplistic view on this is as long as he is happy and you're happy then fine. Depends how much of a trusting soul he is. Not sure what happens about the points/crash though as you wont have filled in the 'official' change of owner slip.
My experience of the DVLA and V5Cs is that you'll have it within a week but think different offices/holidays can take different amounts of time.
Current -: MW E92 M3 Competition Pack / Qashqai+2 Tekna 1.6dci
Gone -: 370Z GT Roadster; BMW X3 3.0d xdrive M Sport; E46 330i M Sport Coupe; Mazda RX8 231; Nissan 350Z GT Roadster; BMW E90 330d M Sport; BMW E92 335i SE; Maserati 4200; Nissan 350Z; Honda S2000; Astra Coupe Turbo; Ford Probe