How much it will cost you to attend university to study law varies greatly. For example, if you attend a university close to where you live, you might stay at home whilst attending university thus avoiding accommodation and some living costs.
If you intend to live away from home, much will depend on which university you attend. Collegiate universities often provide accommodation for all or part of the course. The accommodation charges tend to be cheaper than equivalent private rented accommodation.
Other campus universities may have student accommodation available for those attending their courses. Some of these are subsidised.
If you cannot secure university-supported accommodation, you will be left with the vagaries of the private rented sector where it may be sensible and more cost-effective to rent with fellow students to share the accommodation costs whilst attending law school.