What goes up -
A lot has been written regarding stage 2 on earlier posts. The day consists of a group discussion - try and be yourself and get involved.
Then you will have a short math’s test. Make sure you are up to speed on long division and multiplication, speed/distance/time stuff and basic arithmetic etc
The aptitude tests are looking at your innate skills - very little you can do to prepare unfortunately. I strongly suggest an early night and a good breakfast. When doing the tests try to stay as relaxed as possible, and don't get flustered by others. I personally read all the instructions twice to make sure I knew what I was doing. It certainly helped me, and it you don’t appear be negatively marked for doing so as I passed stage 2, and as I said, I read all instructions twice.
Good luck!