The best thing to do is make good use of bad-weather days (and there are plenty of those at the moment). If you have a student who is solo in the circuit, for example, you can use a bad-weather day to do the long briefing on navigation (which the student will need to do before too long anyway).
What, and spend a whole day working for nothing? I would suggest that Penguina go home and spend all day applying for another job!
You need to get a meeting organised to change the status quo. If the course is sold as self study, then anyone requiring extra ground instruction should pay an agreed amount per hour.