no problem! Have had my fair share of long haul flights in my nannying days, much harder with someone else's child!
Just remember to relax, other wise he may pick up on it. The air stewards are amazing and will help you just ask them.. and if he cries dont worry about the other passengers.. will you ever see any of them ever again? Do what you need to do to make you, your husbands and your babies trip comfortable.. not worry about what strangers think!
I know with QANTAS (I had them on speed dial in the end I called them so much to double check) they make babies under 6 months the priority for skycots.. so depending on how many more babies are on the flight you may be in luck!
I also found a little blanket handy to drap over the cot as its pretty breezy on flights.
you will need to put all liquids and pastes into one of those security bags (the resealable ones they give you- I purchased some more hard wearing ones from Rymans for a couple of pounds) you even need to sudacreme, vaseline pots and the saline spray in the bag...)
Depending on where your stop over is and how long you will be in the airports, you can get buggies (strollers) from most airport customer service desks, you can pre book these, or it can be on a first in first served basis.
Also ask if you can keep your buggy with you till you get to the gate and again to meet you on the otherside in Australia. And buy a buggy bag for it, so it doesnt get damaged in the hold.
I would strongly advice you have some antibacterial wipes on hand too..
You'll be fine.. and when you get here you'll wonder why you worried so much!