Just to preach to the choir, but don't worry too much--it's not soo bad.
I recently did an 18hr direct flight (yes, they have those!) with my 6 mo old by myself and it wasn't anywhere as hard as I feared. Main problems were:
Prob: Going through security with her in Ergo. Have to take her out and take ergo off and I can't hold her and put the Ergo back on.
Solution: kind man with kids at home held baby for 30 sec while I put on Ergo.
Prob: Plane lights strong and in babies eyes once she was asleep
Solution: None really. I don't use a nursing cover so i didn't have that option and all I could was try to position her better. Sitting in the bulkhead row with a baby bassinet was great except people kept walking across to get to the other aisle and many of them would bump the baby--one guy even used it as a handrail, twice! Grr....
Prob: Me needing to pee when she was asleep in the bassinet
Solution: Buddied up with the other single mom on the plane (with an 18mo old) and we tag teamed for potty breaks.
I had no hassles about having her in sling on the plane, but it was an international carrier. And like everyone said, nurse as much as you can!
Enjoy-I think a toddler will be much harder!