Nixon or Opal would be the two closest self-catered, I think... those and the rooms at Freeman's Common... but as has been said, it's mainly 2nd and 3rd years who get into those and you'd have to be quick about it (ie. posting off the accomodation stuff the day you get it - so this advice is probably coming too late!)
The Ratcliffe Rd lot (Clare/Elms/MG) are still a bit of a trek from the campus... 20min walk probably... and I never thought they were much to shout about, to be honest (granted, I've only seen inside a couple of rooms). The people living there seemed happy enough, though.