from the other side of the fence I am a working mum all be it 3 days a week, I found at state school I was frowned upon for working and not being a sahm.. but moved dd to a private school and now the sahm's are in the minority and I am the norm. I guess we all have school fees to pay! Each to their own and expecting DC#4 early next year I may drop my contract hours down a bit more after. Will see... high school fees setting in soon! so unlikely. I think the cost of living means most people cannot afford to be a sahm anymore. It may also vary from state to state and even area to area. I think culturally that once kids are school age the expectation is that mums work in most "more affluent" areas of society. i would suspect that unless you do school stuff, tuck shop, p and c, class room assistant for preppies etc... you would be quite isolated until you made coffee buddies. then as i find I need my income to afford my coffee times ;0)
I am a SAHM in Perth, my eldest is at preprimary now and most of the mums are either full time stay at home or work part time. The drop offs and pick ups are quite social and you met the parents at the park and stuff.