Whirlybird is correct. Dereks' partner, Claire, actually does most of the groundschool. (At least, that's the way it was a couple of years back).
Not actually done any groundschool with them myself, (I was there for some flying with Derek), but I've seen claire in 'action' - she is extremely knowledgeable, and good at passing it on.
I'd say give it a go
ariel