Well, I couldn't really say, to be honest. I expect they won't actually like the idea of a hotel being your place of accomodation. It would be best if you had a real place to stay when you arrive. Can he come to the UK and sort this out before you arrive?
Otherwise, if you're staying with his parents you'd better just come out and say so. If you're not going to be staying with his parents, I'd at least make sure you have arrangements in place at a B&B or something and give them the address. (I'm not sure this will work though, I have to admit. I can't recall if we've had that sort of situation come up here before.)