Whereabouts in Perth are you Miss H? I live SOR and know of a number of 3 yr old kinders where you are not required to attend and where they are only for 2-3 hours at a time.

There is also an occasional child care centre in Booragoon and Beeliar where you pay (I think) $8 per hour and can leave the child there for only a couple of hours. I have used the Booragoon one and it is fantastic. The sessions dont have to be regularly booked either (like a daycare). You just ring a few days in advance to when you require care. My DS started kindy this year and is a June baby and one of the youngest in his class. We used the Booragoon one last year for a few sessions to get him used to the idea of being away from me.

Alot of catholic primary schools are also now offering 3 yr old kinder. Perhaps speak to your local one and see what their costs are and how often you are required to attend.