We've travelled a few times wiht Jenna now, and my bigges tip would be - pack light!! Its so easy to take heaps of stuff and never use it, and if you are in QLD, its still nice and warm in May, so you should need more lighter stuff.
Definitly buy nappies there. But take your formula upin your wown containers as Nat says - no leakage!

I would try and not stress about the solids side of things while you are away, maybe do more breastfeeding instead. Its cleaner, easier and cheaper, and portable! If not breast, than bottle, and just do a little bit of solids. Myabe once a day or something like that? We still had Jenna on our lap when we went out, but most places will have a highchair if you request it in advance.

If you are flying on a catered plane (like Qantas) ring and ask them to provide a baby meal if poss. Then you wont have to carry it.

Take a water sipper cup - bubs will need plenty of that in the heat.

Have a nice time ??

Fi