The Carnatic site is always said to be the most sociable out of the two main freshers halls (Carnatic and Greenbank) but if you're looking for self-catered its unlikely you'll get it at Carnatic, as only some rooms in one of the halls, Dale, is self-catered. The others are all catered, and to be honest I didnt find the food as bad as expected, and it did take off a lot of stress in the first year not worrying about cooking etc! I think its a nice social occasion in catered going to dinner with your friends as well, as I've heard in self-catered people don't tend to eat with each other too much. I would definitely recommend Carnatic!
I'm currently in my first year living in Carnatic Halls - all catered pretty much and definitely the least attractive looking halls but if you're looking for social life and atmoshphere, Carnatic is your place. In terms of it being catered i was in the same position as you hoping for self-catered, and was actually offered a last minute self-catered place which i rejected as it felt too last minute, and i'm so glad i did, the breakfasts are beautiful and the tea isn't bad, it means we actually eat occasional fruit and veg! Greenbank is the second best option - more chances of getting self-catered there and the social life is good too with much nicer rooms, but it still doesn't have much on Carnatic, especially with the size of their bus ques! Hope this helped