Thanks for all the replies on this one.
I am worried about it - having previously applied in the UK when I was a lot younger, the testing sounds very different to the ones undertaken there. In UK I passed the testing with no problems, but bombed the interview which over there involves learning lots of technical stuff and having two controllers ask you technical questions around different scenarios they outline (amongst other things).
My mental arithmetic is not the best it could be, so will just try and brush up on that and I guess estimation would be the best way to go. Thanks also for the tips on writing the instructions down from the interrupt test.
For all of these things, I know there is a lot to be said for accuracy over answering all the questions and that they are testing your aptitude for the job, you either have it or you don't.
It's also good to know it's all multiple choice. Does anyone know what the pass marks are on these tests? Is it like 80% or more like 50%?