We took our dd on a plane when she was 8mo and this was our experience:
we took empty bottles, and cartons of formula on the plane. They were totally fine about it but made us open one of the cartons (we tasted it and poured it into one of the bottles and then fed it to dd). Other people I know have successfully taken bottles of water with powdered formula, but we felt funny about taking a white powder through customs!
We also took jars of food, and again they made us open one and taste it (which was our first introduction to how rank jars of food are, so we never did feed them to dd!)
You have to check in your buggy but you can take it right up to the gate, so you have it the whole time in the departures lounge. They then put it in the hold at the last minute, so it comes out on the carousel, or with 'outsize' luggage the other end (so you have to carry child from plane to baggage collection).
Friends of mine have taken carseats on the plane, but I don't know what airline that was. Some planes have skycots too.
My parents drove us to the airport and picked us up, so they kept our carseat for the week, and we borrowed one from the friends we were staying with abroad. No matter how lax the rules are where you're staying, I would still put my child in a carseat.
Not to worry you, more to warn you, we found that as dd was crawling she was a bit of a nightmare on the plane. Had she been walking it would have been fine, but she was down at ankle level and kept disappearing under the seats, so dh was dashing down the aisle, through the loos, and up the other side to catch her as she came out! So if there's any toy that holds your dc's attention, take it with you!!!