SDM,
I have been studying distance learning with OAT for well over a year now and am just away to sit my final exams. I think you've got the right idea about studying around 2 hours a day. This should put you in good shape for the 2 week brush up course at the end of each phase.
There is a lot of work to get through, but if your determined then you will succeed. The brush up courses will narrow down your studies towards what the exams require. Bristol's feedback, I gather, is excellent and will help your exam preparation greatly!
Good luck with the studies!!