Hi, good luck with the home study, I just recently did the same. I can only comment on the Bob Tait book which I found invaluable, and covered everything in the syllabus in a logical and informative way, especially for someone like myself with no prior knowledge on the topic but managing to pass first time
Also agree with cougar77, make sure you get the most recent book, as he updates it a few times each year to keep up with all the changes. Try and avoid buying someone elses book as the exercises will all be done and there's nothing more confusing than someone elses notes.
Only extra advice is to purchase the online practise exams that Bob has produced for IREX, available through his school and also A.F.T, thye're as close to the real exam as you can get, and a great indicator as to how prepared you are.
And finally, read the questions...............at least 3 times, it's CASA!