Fletch, if you're near Campbelltown the Gymnastics and Trampoline Sports Club there has toddler gym classes that are $7.80 each and pay as you go. They're in the mornings and you can go any morning instead of the same day every week.

ETA - Lollipops is just as good for me - the coffee's better LOL.

ETA - mbear, IKWYM about classes being expensive and to a certain extent I agree that throwing a ball in the park is just as fun but I found with Yasin's swimming lessons that I learnt heaps from them about how to teach him water safety and familiarisation so it wasn't just him learning but me and DH as well.