We flew to the UK when our boy was 3 months old and it went OK!

Get the bassinet seat if you can - so you've got somewhere to put bubs when they are asleep or you need a break.
I fed on take off and landing, but I'm sure you can offer your finger, or a toy, bottle, dummy etc.
You don't have to check in your buggy and can keep it with you until you board - it helped us when waiting for interconnecting flights, if nothing else you can use it to push your luggage around! I will say though the buggy got us pushed through customs and passport control really really quickly.
Take plenty of nappies, wipes and changes of clothes and somethign warm to wear. Bubs own blanket instead of the plane supplied.
Small toys but stilleb prepared for some pacing...
My boy flew over OK but when he woke (his normal time) but it was still a dark cabin, he had trouble with that and was hard to settle those last few hours, on the way back he fed constantly...
You just do what you've got to do, it's all manageable.
I found the experience, not too bad - our toddler was a little more difficult but there were two of us so we took turns.

HTH