Get this one. Sapphire 5850 for only Â£98.
A 5850 for Â£98 is a much better deal and they perform pretty closely anyway. If he does want a 470, he should get this as its much better than the Novatech one and cheaper. But Â£75 extra for a bit more performance isn't worth it.
the 5850 is a little faster than the 460, but not by a lot.
However, I'd look at finding an extra 20 quid and going to Novatech and getting a 470, which beats both those cards, yes, you get the world renowned fermi room heater, but the speed is worth it.