There are a number of options available, with different costs, of course. Clearly anyone planning to commute (from Birmingham, probably) doesn't have to worry.
The University is offering limited accommodation in the University Halls. A link to the application can be found here. It costs 14 pounds a night but preference is given to Warwick-affiliated students and visitors so it may be difficult to obtain. For non-Warwick students in the Easter vacation it is probably easier thing to look around the local area. There are a number of towns that students tend to live in around the University : Kenilworth, Leamington Spa and Coventry all have accommodation which is usually an easy bus ride away from the University. Many prefer to stay in the towns as they have access to restaurants and the like.
In previous years students have decided to group book local hotels or used Air BnB to book entire houses for their group. If you are interesting in going down this route, it is recommended to talk to each other and try to book at a single place. If nothing else, you'll get to know each other and can go out to eat as a group.
In general the local hotels and B&Bs cost anywhere from 40 pounds and up per night, depending on how luxurious you want to get.
The final option is to book into the on-campus conference centers. Warwick Conferences runs several good hotels in Scarman House and Radcliffe House. These are not cheap - coming in at 90 quid a night, but if your tastes and budget run in that direction there are a few rooms available. Note, however, that a number of other conferences are happening in the same week and these are rather full of other (better funded) conference participants.
Whatever you do, please keep us informed. If you have any questions, please don't hesitate to contact Steve Boyd on (0)24-765-73876 or email S.B.Boyd@warwick.ac.uk