My work fluctuates, seasonally, so when it's quiet I write, when it's busier, I write less. What does give, unfortunately, is the house work! My house is a lot more messy than before I did this, but at least my kids are more aware of tidying up after themselves....
to me, though, there's little difference which work I'm doing; I'm at my computer when the kids are at school, normally while they're chilling in the afternoon, and often have a quiet readthrough of what I've written in the evening. I also do school runs, chat to the other mums, do shopping etc etc. so that gives me breaks and keeps me sane.