I attempted the tests last year. The prepack that they send you is a pretty good indicator of what to expect, but it doesn't necessarily cover everything. If you can do GCSE Maths and Physics with ease, it shouldn't be too much of a problem. Don't underestimate the verbal reasoning test though, that test can be very tricky. Spend some time practicing verbal reasoning tests along with the advice given above and you'll be fine. I'll probably see you there!