STM
Airline pilots teaching for free in their spare time is one reason why full-time FIs are so poorly paid in this country. No wonder people complain that many instructors are only in it for the hours - we need to eat like the rest of them.
Thankfully, I think you will find that instructing, which is Aerial Work, counts towards your 900 hours. I'd be happy to do a job share with you if your company would be prepared to match my £13.00 per hour. however....
A