We just flew with DD, 6mo, to Europe. You'll be fine...

For the flight, take a couple of changes of clothes for him, and a change of shirt for you if he's remotely likely to spew on you (like my DD). Take a couple of new toys (try a $2 shop for cheapies that you can chuck out later if they're awful) for distraction purposes.

Time his feeds to be feeding him on the descent. It's a bit tricky because you will also have to have him strapped in with the seatbelt. But that is when their ears get sore, so if you can get him swallowing, he will relieve the pressure and not get upset with painful ears.

Hope it goes smoothly. We've now flown with our DD from Melbourne to Newcastle and from Melbourne to Europe, and it was totally fine on all occasions. Planes mostly make her sleepy.