Hey Grog,
I'm going to just let you know, I have a Childreni, similar age (couple of years older), eats a lot more than yours and is quite active but she too has decided to just go off the food recently.. I'm also in Western Sydney but I don't provide night time heating and as per the drop in night temps lately I can understand why. She's been to the vet just for general checkups and worming etc and is perfectly fine, good size eating small rats weekly. So don't get too worked up by all these doomsayers. Stuff like this happens to some and not for others. As for the beardy I'm not 100% on that nor will I comment to avoid the APS Lynch mob.
And as an fyi, I'm not saying my snakes off her food out of worry, because she's done it before when the temps drop and she'll do it again many times over before her time is out.. I'm pretty sure it happens to a lot of snakes especially with colder weather creeping in.
Mighty_Moose