Hi JJ. Firstly, you are right - that's what this forum is for, so don't worry about asking for advice!!
My few tips would be:
Take a stopwatch, but turn the beeps off!
Sounds simple, by by allowing yourself 30 secs for each numeracy question, you could answer 24 in the 12 minutes given. Do NOT stare at a difficult question for too long - you'll just get flustered and lose precious time. Don't forget to leave a blank for your missed answer though - I nearly didn't!!!
Personally, I practised for quite a bit before I went, in terms of quick, simple calculations. Even knowing multiplication tables is helpful, and a having a good idea of long divisions/muliplications. I'm not saying that you'll definetly need that stuff, but it gets your brain thinking in terms of numbers well before you sit the tests. Just look for everyday examples where you can apply simple maths - adding up your shopping, etc!
Above all, good luck mate. Just do your best to be relaxed when you walk in, and don't focus on your perfomance before. You can do it, I'm sure!
FTL