G'Day
Self study isnt a bad way to go. Allow at-least two weeks per exam, Performance may take a little longer. I just booked the exam two weeks in advanced and thats all the inspiration I needed.
If you have the time and money, the full time theory courses would be ok. But if your trying to juggle work/school, then the self study would be the best option.
I recommend the Bob Tait CPL books, to the point and easy to understand. At the end go and do the practice exams on the Bob Tait website.