I have done my Bristol course about 5 years ago.
I Personally prefered to read the material from the paper print as I find I can spend more time reading off paper rather than off an ipad/computer.
I still have the books should I decided to look something up, although a quick search on their software makes life a lot easier.
I reckon it is all personal preference when revising for your initial ATPL.
Best of luck with you ATPL