You're right in thinking that Jarratt Hall has all the intermational students and no atmosphere. I had a friend who was there who chose to move after a couple of weeks, so don't worry about being stuck somewhere you won't like for the whole year.
Best self catering place in terms of student atmosphere would be anywhere on the Vale, really. Elgar Court doesn't seem to have such a great atmosphere, while Tennis Courts and Aitken wing all seem pretty lively. I don't know anything about Maple Bank.
The liveliest places are without doubt in the halls, but you have to remember you would be paying an awful lot for accommodation shite furniture and shite food.