I did the OU PGCE whilst working (almost) FT at school. Warning - you can be a good teacher or a good student teacher, but not both. Plus you may need to negotiate time in another (state/non selective) school, which, if it doesn't interfere with you own school, may be at the end of term (where sometimes it's difficult to get the right time of teaching). But I did mine about 10 years ago. Maybe someone else can offer a more recent perspective.Good luck!