I did mine 11years ago and instructed for 5 years. I had to do 3 weeks unpaid ( that was a commitment thing
) I had to learn all current aspects of motorcycling law IE who needs a CBT, MOT requirements, learner laws, Highway code. I was then put through bike training which was at first hours and hours of observed riding and basicly bought up to scratch. They then tought me how to ride with a pupil, safe distances etc so I wouldn't unnerve them by riding to close.
I had to do several rides where I had to provide a running commentary with another instuctor so he could make sure I was being as observant as i could be. Most of the rest of the training was being put through the same course they would give a novice rider so that I learned the test routes and the course schedule. It also gave me a better understanding of what it was like to be back on L plates. And they were a lot stricter on mock tests with us, we were allowed next to no mistakes. All this was done and monitored through (what is now) the DSA
Almost wish I had kept currant.