Bath is a very expensive city anyway ..
Don't know about the communal bathroom, I had my own bathroom in the halls :/ . I think it's manageable though .. Don't spend extra money on en-suite room, I don't think it worth it.
My accomodation isn't managed by the uni and I pay £320 per month. We are 4 sharing the house, 2 bathrooms and the rooms are really good.
Up to you to see what you prefer but you should have a look at the private accommodations too. Some people may look for housemates to "complete" the house.