Hi,
Firstly, good luck with the course. I found it the hardest yet most rewarding flying that I had done in the previous 500 hours. Of course, instructional flying is even harder and more rewarding, so it's worth the effort (and expense!)
I found that every aspect of my flying was deconstructed and then put back together again. One surprise for me was that I we didn't do the exercises in order, we hopped about from say, ex 6 to ex 15, back to 7 & 8 as conditions dictated. This of course is exactly what happens in real life.
So, how to spend your week and 2-3 hours flying time? You will spend your 30 hours on the course (and your instructional career) flying from the right seat, so it might be a good idea to do some from there. Even just being a passenger in the RHS can help; spend the time trying to overcome the parallax error reading the instruments, especially the balance ball. That's the one instrument I wish I had duplicated on my side, but eventually, you'll get used to telling with a fine degree if the a/c is out of balance. You ought to be able to consistently fly plus or minus 50 feet and 5 deg whilst chatting with a mate.
In my view, it's a waste of time having to have CPL or higher Theoretical Knowledge for PPL instruction. What is needed is a thorough knowledge of all the subjects as understood at the PPL level - get hold of a confuser and make sure you can do all the questions as seen by a PPL. We got regular tests from a question bank and it was an eye-opener as to how much I had forgotten about the basics. The less time you spend on the course re-learning forgotten PPL TK, the more time you'll have to learn how to put it across.
By the way, if you have no more flying ambition than to instruct, you'll only need a medical every year, rather than every 6 months. I let my Class 1 go on reaching 65, as the CAA wanted me to spend loads on a stress EGC, back to Class 2 now for instruction.
TOO