In terms of picking rooms, you get an options form when you can select from:
- Single Bailey
- Shared Bailey
- Ensuite self-catered
- Single/non-ensuite self-catered
In order of preference, so you could go for a Single Bailey room then apply to ensuite stuff if you really didn't want to share.
I'm in one of the non-ensuite buildings and there's 5 people to a bathroom, this is the max I think. You can also go for the meal package if you don't want to cook.