In my humble opinion sod preparing before you start , start now , if your getting the books then why not start studying them . Both the above mentioned series are excellent although I have to agree with pchappo the AFE ones do seem better . Wouldnt it be nice of on one of your first attendances you could pass air law , thats first solo sorted then nav qual x country sorted . a lot of it will seem alien to you at first especially with no flying experience but the majority of air law is remembering facts and figures and other stuff .If you werent aware you need to pass air law beofree you can solo and speaking from experience theres nothing worse than being ready to solo and still having an exam to take . think about it the more exams you can pass earlier the less you have to worry about when your flying
good luck I wish you well you will love it