Just have a $1 woolworths/coles bread and get a spread. Their Maggi is a little different but you can have Indomie which is an Indonesian brand and its halal. There's some asian stall near Canberra Centre which sell the Maggi that Singaporeans are used to, but there's only Maggi Curry/Kari. Please do your due diligence and watchout for some sale item and inspect the expiry date. I've bought a 3 for $5 nescafe and turned out to be few months expired. But still, these types of sale will help you save some bucks, especially if you are a backpacker.
There's only 5 stores that I've eaten at so far, Papparich , Turkish halal pide , Mr Zee and Kingsley Chicken which have their halal logo either on website or on site. There's one more Taste a curry, in Queanbeyan. The stall serve halal meat, at first I went in and the owner said he was muslim but on the next visit, I ask where's the nearest mosque and he couldn't answer...So its a little dodgy.
Just trust your guts, but I decided not to go the places which I'm not comfortable with anymore. Most of the items/brands that you see in Singapore that have halal logos, does not over here. So do your own checks...