Definitely give it a go.
The hardest part for me was being motivated, I had a minimum 6 hours a week to do & my plan was to do an hour or so each night but I found it all to easy to leave it & a lot of weekends I ended up doing 4 or 5 hour blocks of work - not in the plan! And working during the day is hard with little ones around.
BUT as you said, there are no extra daycare costs & the fact that I could tailor the hours that I worked to suit my days was great.
I think your suggestion of 10 hours a week is great, manageable to start with & will let you see how it's going to work for you.