I'm finding the Thom set of PPL books excellent, everything is explained in plain english and the key concepts are all repeated throughout the series to re-enforce important sections.
The Q and A sections are great to make sure you have understood each part of the books.
Originally Posted by femaleWannabe
By the way, amazon do the AFE books for about £13 each - cheaper than the afeonline site.
I got all my Trevor Thom set from Amazon and saved around 60% on the set.