It’s so hard to know what you will be able to do! I think afternoons would be a great suggestion, as like you say in schools you always end up being asked to do something extra. Plus aren’t the afternoons in primary more varied (my daughter does her maths/English every morning and then has other subjects in the afternoons) so would be a nicer way to ease back in.
Don’t be afraid to ask for what’s best for you not just what’s best for the school. Well all get there eventually I’m sure!