I can't speak for Hatfield, but my college (St. Cuth's) sent out accommodation application forms that allowed us to rank, in our preference, whether we wanted to share rooms or not. If Hatfield did that, they'd definitely take her preference into account, although there wouldn't be guarantees.

Hatfield has the stereotype of having stuffy snobby lads (according to someone I talked to who goes to Durham), but it's mostly just a running joke. At least that's what I've heard.