600 notes will get you something nice south of the river.
I really enjoyed living on British road (BS33BZ), there were a couple of restaurants on west st that were really cheap and friendly,decent thai and an indian that could seat about 40 people between them, easy walk to north st pubs and bars for nicer eateries and only a 30 min drunken stumble back from town.
Everything from there to the river is pretty nice, things get more expensive once you get between North St and the river.
If you’re looking to get out to Swindon on occasion then you can go south out of Bristol and round the ring road (against most of the traffic) and then the A420 is a pretty clear run up to Chippenham (and good for a blast)used to take me about 40 mins in the mornings.