Both my bubs were born in October and November and I'm in Brissy so should be pretty similar conditions for your bub

The one thing both of mine lived in was short sleeve/short leg all-in-one suits. That's basically what they wore at home during the day. I had oodles of them and used them all.

Don't go too crazy with the Bonds suits just buy a few in 000 only. Don't bother with 00's because by the time bub is in 00 it will be too hot for them, day or night. I found I used them most with DS who was born early October - I used them for him for a month or so. DD was born mid-November and I used them maybe twice for her since it was way too hot by then. Those things are very warm!

Singlet tops are good too. I wouldn't take my kids out of the house in a singlet and nappy but I did have lots of cute little "dressy" singlets that they could wear on really stinking days.

Totally agree with what's been said about cute outfits too - they're a total pain to get on and off, they have to be ironed (and you'll have neither the time or the inclination to do that), and they don't look great on floppy little babies anyway. They just get all bunched up and baby looks (and probably feels) horribly uncomfortable.

Make sure you get quite a few large (120x120cm) muslin wraps, they're invaluable in the summer here because it's too hot to wrap them in anything else.