Not been to warwick but have been to many open days before. Its worth looking at the course and its modules and see if you have any questions from there . Hours of study/lectures/support/internships etc.
Definitely check out the department and also the subject talk. Accommodation, you dont have to visit every one, but plan to look at ones you are interested in like ensuite or standard accommodation. No point looking at accommodation thats over your price range.
Also go and visit one of the eateries, sometimes unis give a voucher with some money off when you visit the registration area. If you do not visit the registration dont worry, theres alwasy students everywhere to give you a helping hand as to where to go as its not essential you need to register in person, although you sometimes get some free stuff like a tote bag or a mug. Also registration will have a programme should you not have one sent on line.
The programmes are great to check out when and where the subject talks are, accommodation and also anything that grabs your interest. Ive been to study abroad talks, or accommodation talks, or visits to the student union.
Get there early. About 20 mins to half an hour before the open day starts so we get a good parking space.