Just buy the book “The Official DVSA Guide to Driving Goods Vehicles” read all the sections, and then keep revising the driver hours periods.
The week before your theory and CPC studies you want to read it again. You should be able to breakdown all the driver hours & rest rules verbatim. The book will help you out when you’re in the job as well. I bought the other books but they’re a waste of money. You just need the one book and you will pass first time on all the questions. 