I'm on maternity leave at the moment and am thinking of asking to go back 0.8 (I was full time before).
My reasoning:
i) I am the only teacher of my subject -- I can easily cover the lessons in that subject in 0.8, although unfortunately due to the sixth form timetable it's likely to be over 5 days not 4. As the only subject teacher, my negotiating position with school is good.
ii) 0.8 will mean I may be able to get away with paying for 2 or 2 1/2 days' nursery rather than 3 (DH doing 1 day, DM another) -- being part time will also mean school can't give me sole responsibility for a form, which means a good chance I can get the co-form teacher to do some morning registers, so less stress with drop offs at nursery (only just enough time to get from nursery drop of to school in time for register)
iii) 0.8 will not be enough hours to be required to teach my second subject, one I was forced to take on in order to qualify, am not good at teaching and have ethical objections to teaching. It is one offered at KS4 which means a lot more marking as I might easily have 4 or 5 sets each with 30 students. I really don't want to have to discuss my feelings about the subject with the (nice) Head as it is her specialist subject!
My DH feels I might as well go back full time as I will be giving up 20% of my pay for not much less hassle -- but we don't really need the extra money, whereas I think I will only just be able to cope with the planning and marking for my one specialist subject, while doing the second one as well will be too much.
I had a previous career before teaching and if I found in the future I needed the full time salary, would take on some bits of different work (or do external examining/tutoring) if school wouldn't put me back on a FT contract.
Advice please? DH is a lecturer and thinks it is the same, so I am finding it hard to convince him of the difference the extra marking, second subject and full time form teaching would make.