I know you posted this some time ago however having just seen it and as a current first year student who would have loved to have insight on halls I decided why not share my ramblings concerning accommodation.
I would defo advise self catered as you do get to learn to cook for yourself, top tip (its not that difficult, its called reading if you follow a recipe!)
In terms of sociability I will repeat what I'm sure you have already been told, most accommodation will be sociable, after all very few people in the world want to be loners (its not really a life plan option that fills many with hope spending evenings alone) however there are certain accommodations in bham that are know for being 'more social' which basically means, people who like to go out more and spend more time procrastinating with others than procrastinating alone watching tv in your room.
As an unconditional you have a very priviledged position as essentially you have 'first dibs' to all accomm. I would frankly advise to pick TC a.k.a. Tennis Courts.
Many will say I'm biased as someone who lives at TC but I promise you many of my friends in mason and pritchetts and liberty and maple are jealous of people that live in TC. Why? We have loads of halls events including: 'I love TC, donuts night, TC v Mason, TC v Maple, TC goes terrestrial' and many many more. We have awesome chants which are surprisinginly easy to learn even when drunk. The people who enjoy going out and spending time with people often pick TC because of its reputation which is why its reputation theroetically continues. We have like 700 people so one of the largest halls and are the closest out of those on the vale.
We are cheaper than mason (trust me in my opinion paying an extra £1000 for your own toilet is just a waste of money however TC even provides some ensuite blocks now which I have to admit are very nice)
We have bigger kitchens/living rooms than maple, like twice as big which means bigger pres parties, and unlike many accomm we are set out in blocks which you get to know the people in very very well (around 30 people) and I have to admit picking TC was my best decision in a long time so do it!....or don't whatever haha Hope this helped