I promised to give a decent reply and now I've awoken from those morning blues, here goes:
If you're worried about memorising formulas, there's no need. If this hasn't already been explained to you, the formulae is on the first page of the GCSE paper, so all you need to do is understand what to substitute.
Here's a GCSE higher tier mock exam (non-calculator):
http://downloads.bbc.co.uk/schools/g...kh1_nocalc.pdf
Here's another GCSE higher tier mock exam (calculator):
http://downloads.bbc.co.uk/schools/g...ockh2_calc.pdf
Some algebra, particularly simultaneous equations:
http://www.youtube.com/watch?v=k-HcCU0P7A4
Some volume:
http://www.youtube.com/watch?v=WPyNj...feature=relmfu
In fact, just go through all of this at your own pace:
http://www.youtube.com/user/HEGARTYMATHS
Should be well worth it, though. It's much easier at the higher tier to get marks than it is at foundation level, really, so if you're already in higher it's good you're staying there. Just revise as much as you can and it'll all be over in a week or two.