I worked when I was a single parent, but this was after the 12 months I had to wait on the child care waiting list. Before that, I worked one day per week while my oarents watched DS (the absolute maximum I could ask of them, with them both working fulltime).
i still qualified for some PPS when I worked the 1 day per week thankfully.
I think you have very romantic ideals in your head of what single parenting is. My DS's father was employed while I was with him. Pretty ironic how he quit work as soon as we broke up so I received a grand total of something like $2.86 a month. Wooooo hoooo!