If you do have a difficulty with CRP5, Pooley have produced a CBT CD-ROM for use with your own home computer, with good graphics and with sound. It explains it all very clearly. It costs £23:50. Everyone I know who has tried it has found it very useful. It has also been well reviewed by the aviation press.
I should point out that we at OAT must declare an interest. We created it for Pooley and we make a profit on every one sold. You may therefore wish to bear that in mind when reading the above recommendation.