It obviously depends on how expensive the area is, how big the room,and also how close to uni, how many people sharing with etc. I have bought my own place now and pay the mortgage, but last year I rented a large room in a shared house close to campus(would have usually been the lounge if the house was not divided up for maximum profit) for £340 per month. All bills had to paid on top, except for TV license, which the landlord paid. It sounds like a lot, but as actually cheaper than halls! Maybe find that price out and use it as an indication, or ask your uni's accomodation office for a price guide.