Hello
Have you been to visit the Uni? If not it would be worth a visit, the next open day is Wednesday 8th June, at the open day you'd be able to go on a tour of the halls (although due to how busy it gets you can only do one of the two different tours)
I actually live at home as I don't live that far away so I have no personal experience in the halls etc but i'll try to help!
Halls of residence typically cost £185 - £280 per month. Which is very low. The average rent per week in University halls of residence £57.
As for everything else, it really will depend on you.
Food - if your happy to buy own brands then it shouldn't cost you too much, just learn to shop wisely and you'll be fine. e.g. buy large bags of stuff like pasta that lasts ages as bulk buying usually works out cheaper!
Activities, well really it depends what you want to do. Nights out can be very cheap on a monday, which is student night. But it does really depend on what you want to do really and just spend your money wisely and you'll be fine
Plus you could always get a job if you are worried about money.
If you want I can try to get intouch with some friends who have lived in halls and try and find out some info from them, but I really would suggest you come to an open day!
xx