Have you or any other part time teachers worked for the school you're emplyed by but also worked supply via an an angency on your other days?
I am a PT teacher but don't want to up my hours at the school I work in as it ultimately means more responsibility (more lessons to plan, more paperwork, more twiglights etc.) and it obviously wouldn't be flexible. I like the idea of signing up to supply agency so I can do an extra day here and there (maybe 1-2 a month at most) for the additional pay without the other commitments that come with that. I simply turn up, teach the pre-planned lessons, mark the work (which will probably end up in the bin anyway?!) and go home.
If you have this arrangement, how is this perceived by the school you are employed by? Any downsides?!