unless of course you have gone for the reversing camera
seriously though, for the sake of £200, I'd go with the '08 model
The only difference is as FWH says above - the parking sensors - but you can't get them for £200, and it will indeed be worth marginally more come re-sale time.
On the flip side, if he has an '07 ready and waiting right now, vs a 2 month (or more) lead time on an '08...