They're just flies, they don't bite. After a day or so, you'll get used to it. Eat indoors/cover your food, and don't yawn outdoors.

Flies, I think, are typically an early summer problem. You need heat, then rain, which is a common pattern in early summer. By Feb, you'll only get the heat, not so much the rain. I'll worry more about sunscreen than insect repellents.

If flies worry you to an extent to change your itinerary, don't forget about the number of venomous snakes and insects that live in Australia...!