I was in the same place as you,
Check out forums like 'the student room' and various other ones, google search it should do the job.
I found
Speed Distance Time | OASC: RAF Officer and Aircrew Selection Centre really helpful. Self explanatory, at the FATS it also goes into detail with Algorithms and stuff (Networks, maps - working out ETA's)
I also bought a book called Military Flight Aptitude Tests, off amazon. Although designed for the yanks it has a certain amount of crossover with the British Tests.
Hope that helps.