Unlike some other subjects, mathematics is a subject where you need to bring very little with you!
Every module will have recommended books, and you should plan to buy at least some in your first year rather than rely on the library for all of them. The downside is that maths books tend to be expensive (typically 30 to 40 pounds from new) but we will try to recommend reasonably priced ones. You can also look out for second hand books being sold on campus (many second years will be trying to sell their first year books) or online sources such as the Amazon Marketplace are good places to look. Most modules will provde printed lecture notes for cost price from the Undergraduate Office (2 to 3 pounds) which you may find are sufficient for many of the topics you will study. You may find it useful to bring your old A-level books and notes with you too for reference.
Surprisingly perhaps, a calculator will be of minimal use on the maths degree! As you progress the mathematics you learn will become more and more abstract and you will find that the main use for a calculator is adding up how much money you've got left to spend on the weekly shop. Calculators are not allowed in tests and exams from the mathematics department, and exams from other departments will not allow calculators that are programmable, have more than two lines output or with a graphical output. So the rule is do bring a calculator, but don't think you need to spend a lot of money on a fancy one.
Bringing a computer with you is not essential. There is a minimal amount of computing involved in the first year syllabus, but the University has an abundance of PCs around the campus for which you will have a login code before you even arrive here. If you do bring a laptop or tablet then there are Hotspots around the University which will let you log in wirelessly and every accomodation room on campus should have a network point. Please do not use laptops in lectures unless you have a medical reason for doing so, it is distracting for other students and to the lecturer. Also follow the advice on the IT Services pages, bring a security cable with you and make sure that it is insured!