I am a teacher working 0.6 (3 days a week)
DH often works away, and even when he doesn’t leaves at 7 am and back after the children are in bed. He does do what he can but realistically isn’t around much. Obviously this means everything to do with the children and home falls to me. The one bit of respite I’ve had is that during school holidays they are in nursery for a couple of days so every 6/7 weeks or so I get a couple of days to myself. This keeps me fro losing my sanity 
Obviously when they’re both at school this will change and I’ll have them in the holidays so AIBU to refuse to up my hours or even ask to to 3 days spread over 4 or 5? I really will value a couple of short days a week to get stuff done and just breathe a bit!