Assuming you're starting out with kits and adding the kilo of sugar as per the instructions? Post your recipes, even if it's just the name of the kit. You'll find that most kits for making "lager" are supplied with an ale yeast (or sometimes a blend of ale and lager yeasts) under the lid. Experienced kit brewers (or a bit of Googling) will help you identify if this is the case.
Some of the first advice new brewers are often given is to chuck out the yeast that comes with the kit and spend $4 to get a packet of something fresh and better suited to the task. For lager, something like Saflager S-23 or S-189 would be the go.
In Brisbane you won't need a heat pad to make lager - in fact you would probably still need to actively cool your fermenters as lager yeasts work best at about 9-12c. A potential problem for SEQ winters is that without temperature control, your brew's average temperature could end up in a kind of no-man's land that's slightly too cool for ales and too warm for lagers. Depends if you're brewing indoors with the heating on, etc. Somewhere with a stable temperature is best.
Your best bet might be to get some packets of Safale us-05. It's an ale yeast, but reputed to produce clean, lager-like results if fermented cool (like 15c).