Thanks for your reply Eno. I still think preparing/practicing for these kinds of tests could influence the result. i.e. if someone made a clone Compass test, you would obviously do very well when you sat the real one.
The idea is to see how well you do given little previous exercising of those mental abilities ... i.e. natural unbiased ability. Practicing for them specifically will give you a false indication of how you'll perform when learning further skills during a pilots course.
However, just for testing yourself I think there is a need for home versions; the RAF obviously thinks so. I shall give it a go when there is time, but I'm a lot busier now than I was 24hrs ago when I posted it!