What people don't admit is that in a lot of ways its easier to work.
When I was a sahm I did everything, as was fair.
Now I'm a working mum DH does before school and I do after - I leave very early, at 5:30am so DH takes the youngest to school after seeing the older ones off to the bus stop. I'm home in time to pick them up from after school care (in our case as we are abroad after school means from 12:15! The youngest is in Kindergarten til 3pm - I pick him up about ten to, and the middle one in lunch/ afternoon/ homework club til 3pm)
There is proper supervision and help at homework club - as a sahm I found homework supervision more frustrating than I had ever found the toddler years, despite the fact I used to be a teacher! 
The kids do a lot more now I am working - eldest voluntarily does her own laundry, younger ones (9 and 6) carry theirs to the machine and put their own away. They pack the dishwasher and unpack it, and take the bins out.
DH does far more and is beginning, slowly, to take a bit more of the mental load.
I have to work weekends once a month, which forces DH to actually cook and ferry kids about at weekends - before I did all of that.
I'm doing 26 hours a week atm and will be doing 36 hours from September, but it isn't any harder than being a sahm as the more I'm out, the more DH and the kids do, plus some of it is outsourced to homework club etc :o
We will probably get a cleaner at some point - atm it is partly that although I hate cleaning I don't really want a cleaner, I have hang ups
but I'll get myself over it once doing full time :o (They are also quite hard to find where we live, so a bit of effort required getting an arrangement set up).
Its no harder magicat in fact its easier to work and share the domestic load than being absolutely and solely responsible for every single little and big thing child and house and education and clothing and food (planning, shopping, cooking) etc. related relentlessly, 24/7 365 days a year while children are small.