you won't run out of money if you go out twice a week. you can do a night out on a tenner once you learn how to do it properly. most people at bristol dont need to be prudent, but if you get ******ed before you go out, u only pay club entry, maybe one drink and a taxi (for stokey B's, sometimes for lazy cliftonites).
you can't just be a hermit (well, unless youre like that anyway) or you'll go mad...
you'll be amazed at how quick the first year will go, so make the most of it. i've gotta start actually doing work next year and i'm gutted, but at least i know i've had a fantastic year...