Definitely have a look at the CBAT blog, and try the app too. However, this will simply give you a bit of an idea as to what to expect. To put things in perspective, I went through the CBAT blog and familiarised myself with some of the screenshots of the test and read the descriptions. I didn't have the app, but had a play around for about 30 minutes on someone else's tablet (who had it) at the ASP. The app is good for again, just familiarising yourself with the tests (of which they are a relatively good mimic of).
I second what The Ayatollah said though; get a good night's sleep, don't stress out too much. Try to relax, make some new friends and enjoy your time down there. Being relaxed, comfortable and fresh when in the tests will do you a world of good. I ended up getting a high rec, however I think that the most important thing (for me anyways) was to just try to be in a good zone when you do the tests. Even finding a quiet space in your room, or somewhere else, where you can just chill out and get your thoughts together before entering the test room (you'll note the prayer room right next to the testing room - I was in there!). And also, very importantly, take advantage of the rest breaks in the test to stroll around, get some fresh air, and "re-zone" yourself.