If you get the info about the residential course with Guildhall, they might send you a self-test maths book. This is useful as you can identify your own weak points to brush up on before you start the course.
If you've got even a basic command of maths you won't have a problem- I actually quite enjoy the challenge that is Gen Nav!
PS Send Clowns... it took 4.5 minutes, answer for you tomorrow!