Dave is your son intent on any overclocking? If not, that motherboard and cooler are overkill. You could easily save that £50 off the cooler and use the supplied one with the CPU. Also, has he thought about small form factor? I built my wife a SFF pc a while back and it's awesome, it has great components in it and is pretty small.
This is the case I used for my wife's PC:
Bear in mind that it needs ventilation on the sides though. Obviously the sides will be covered up. Don't think you'll be compromising on performance either, you can pack a whopper into these tiny cases, and PC enthusiasts are lapping them up.
Also, is he really going to need 3tb of storage? That's a lot of storage. I have a 2tb drive in my PC and even with my entire games library and my prolific support of shady download sites, I've never gone over 1,5tb.
Another thing to bear in mind is whether he'll be using a wired or wireless connection, if he's going wireless, he'll need a wifi card too.