It feels like a million years ago that I sat the GAMSAT (aka the Grimsat) in order to get into medical school. In fact, it was 2006, but it still feels like a distant memory. Perhaps I have suppressed it, as it is a nasty exam and anybody who walks out thinking that they have done extremely well is either deluded or too intelligent to be in medicine and should just go straight into research.
Anyway, for all those who are sitting this rough exam tomorrow, GOOD LUCK!
My advice: don't fret, treat it like a practise run, eat well before, during the breaks, rest well before and afterwards, and don't forget that your results depend on where you land in the pack, and everybody else sitting there is human, too. (Everybody except for those hyper-intelligent people who should be into research, and there aren't enough of them to worry about.)
Remember, no matter what, there is always next year. In the meantime, enjoy your life. There are more important things than getting into medicine. :)