There are no self catered options at any colleges other than Josephine Butler and St Cuthberts. Every other college is fully catered, and you CANNOT opt out (ie. even if you didn't eat any meals provided for you you'd still pay the catered cost). There are kitchens, but you aren't expected to self cater (there are no cupboard spaces, there are hobs but no oven and the fridges are shared).
Aidan's also has lots of shared rooms, and you also can't opt out of that either unless you have a valid reason backed up with evidence (like a medical reason). However they do send round detailed questionnaires in which you can detail why you'd prefer a single room if you don't want to share. They also use these to match people up to similar people - most people really like their room mate if they end up in a shared room, they do a really good job in matching them up! Most people have single rooms though. Shared rooms are now slightly cheaper too, it may not seem that it's by a lot but there used to be no difference in price. Also £5 a week difference really does add up, when you start looking round accommodation when you don't live in college you suddenly realise how big a difference £5 a week makes!