in fact i do a similar thing but from home (so possibly safer), as i work from home 2 afternoons a week with no childcare. they are 18months and nearly 3
so on those days i pick up from nursery at 12, home for lunch together.
1-3pm they sleep - i work
3.15-4.15pm they have snack/drink/ and play at the table with toys/easy puzzles/ crayons/ playdough/ or latest is waterplay in bowl on kitchen floor with spoons etc.. (in just nappy/pants) - i work at table on laptop, adding encouragement every so often
4.15-5 - i stop work and we all go outside for run/walk/play/jump in puddles
5-6 -i work on laptop in lounge, i set up so train track/lego etc and they amuse and play with themselevs or each other.
6-8pm- we eat/ read/ bath/bedtime.
8pm onwards i catch up if needed
so 3 days a week i work out of home.
and on those two days home i work 8.30-11.30 alone (3hrs), then roughly another 4 hrs once they are home , 2 hrs whilst asleep and 2 hrs whilst awake. dh drops them at nursery at 9 on the way to work so we only pay for 2 1/2 hours of childcare on those days.