Will you be taking some supplies from Australia, or stocking up when you arrive?
As far as puddings go, locally there are ready-to-eat custard cups (Snack Pack?), also small tins of creamed rice are now available..... Although you'd probably have no trouble getting through a full sized tin.
These are a non-heat item: http://www.stdalfour.com.au/products/fr ... o-go.shtml
Not sure whether they'd be energy dense enough. But they aren't bad for tinned meals.