In my experience, I wouldn't get in too much of a stew about it, save to say basic O level/GCSE maths is fine. That is all I have and am certainly no wizz. You may be taught some formulae that sound baffling at first especially when transposing equatiions. However, if you listen to what you are taught by a good lecturer, you will realise that they tend to explain how they arrive at that equation. If in doubt, just remember the resulting formula. It is all you need, and that will be basic O Level stuff. O level taught me trig and if that is not the case now, I would certainly agree with S.C that that is important.
With regards to CPL IR flying maths, certainly don't panic...I did.
As many will tell you, what is reasonably easy on the ground becomes neigh on genius material when flying and as such, there will be many tricks of the trade shown to you for airborne calculations.
Hope this helps,
Harves