Basic maths and physics is all you need. On the maths side, trigonometry (triangles and circles), sin, cos, tan is the main area, as well as being able to transpose formulae. On the physics side it is the basic laws such as Boyles, Charles, Newton, etc. Nothing too extreme. I was rusty when I started but soon got back into it.
I am with Bristol and when you start module 1 they offer a short refresher course for a small fee to bring you up to speed with what you need to know. Speak to Alex about it if you are interested in this.
Regards
NH