I never studied geography before, i opted for it out of interest. If you are interest in geography and feel it will be a pleasure preparing it, then go for it. Since I hadn't studied geography before it took me a lot of time gathering material, arranging notes. But i had the time. I started preparing for 2008 exam from June 2007. That whole summer i spent fishing out books, simultanouesly searching the internet. For physical geography it was difficult to get a good book initially. I prepared chapters from a Pakistani author's book and there were so many mistakes in (especially spelling mistakes) that at the end of everyday i would search every term on google to make sure what i am learning is correct. Then i came across the Exam Cram series for geography, it really helped. The Oxford University on Physical Geography i came across by accident just 2 months before the exam.
I had to reprepare most of physical geography chapters again from it, it didnt take so long as the concepts were already formed. For geography paper one I didnot prepare climatic regions at all (it takes a lot of your time and if you look at past papers there is just one question from it, you can prepare its MCQ's from Exam Cram Objective section).
I didnt take tuition for any of my subjects. I consulted cssforum, google and very rarely an uncle of mine who is a CSP. The notes i mentioned are all from wikipedia, from my review of past papers for geogprahy i prepared notes for topics not in any of the books. Its just that they are properly formatted. Give me your email address i will email them to you.