If instructing the student is counted as flight crew not pax. Even if they don't have a medical or license.
So the 90 day rules does not apply. Also if you don't have an IR you don't need to have one circuit at night for the same reason.
This is one of the discussion topics on the instructor seminars.
The only T/O and landings the caa seem to be worried about is the night qualification. Had a log book returned because in the remarks we hadn't put "x full stop landings" next to each flight with circuits. They only gave credit for 1 per sortie.