1. Commercial food items are generally ok.
2. Leave everything in originally sealed packaging.
3. DECLARE anything you can consume. Apart from the forms you will be given, Quarantine agents will ask if you have anything to declare, and then you tell them what you have. They will be very nice and polite about it. You can basically tell them you have half a dead cow in your bag, and they will very politely say "sorry, not allowed ". But since you have declared it and ticked the Yes box, there will be no fine. But try to sneak in a banana, and they could get agro and fine you. (And fines have at long last significantly increased).
4. If you would get upset about having to give up your food items at Quarantine, don't bring it. (Unlikely, judging by what you describe).
5. We DO sell nuts in Australia.
(and bubble gum and nylon stockings)
😉