Jamwo,
When I had my assessments at two UK flying schools, and given my relative lack of interview experience, I found it really useful to get some books from the local library on professional interview technique, as well as some on aptitude tests - both were a great help.
If you're looking for PILAPT preparation, as opposed to DLR preparation, which I believe is what SkyTest offer, there are a few that I know of, listed below:
Cockpitweb: pilot aptitude test,Pilot computer test software,numerapt,numerical reasoning, psychometric test, mathematics,job application,pilot recruitment,IFR Training Software, ATPL Pilot Training, Pilot Training flight simulator, aviation training
PAT | PilotAptitudeTest.com - Practise for COMPASS Tests and PILAPT Tests
Pilot Aptitude Test Trainer (PATT)
Hope this helps, best of luck!