Joining this one a little late, but the only thing I would add is don't fall into the trap of throwing little snippets in to show how much you know if you aren't prepared to be questioned about them. (E.g. If you have heard about RVSM but don't really know what it involves, when it will start, potential problems etc, then don't start digging the hole!)
Early comments about the computer tests are spot on: Use ALL the available practice time (I did on the crashing numbers until it told me to get on with it!!) and then concentrate on stopping them crashing. If you manage to get a few of the sums done at the same time then all well and good. There's no point in killing 400 people while you're concentrating on the latest banter in the Ops room...
Above all: Be yourself. If you're preending to be something else, you'll never keep it up. The system will catch you sooner or later.
Best of luck.