We flew from Florida to Alaska with my twins and it was better than expected. Hopefully you have a flight at night as we did because they slept the entire time. We did bring a stroller which was nice during our layover. We brought sanitary wipes to wipe everything we could down before babies could touch and had sanitizer for ourselves. We got a freezer bag from Amazon for breast milk and brought extra sandwich bags for ice which you can ask for on the plan or at a restaurant. Try to only bring what is needed and one extra just in case. They were also eating baby food at the time and we brought pouches of baby food. Airports do have those motherhood stations incase you need to breast feed or pump in private.
Went to poland for 2 weeks at 8.5 months, and we didn't bring a travel stroller. Best decision we could have made. We did bring the tushbaby +snug attachment, and rented a car seat while we were there. See what you can buy there, and bring a 2 day supply of whatever you can buy there to give you enough time to get it. Oh, and bring 2 to 3 back up outfits for the plane with plenty of diapers. Breastmilk- i used the Ceres and the medela bottle bag with the frozen block for transport of fresh milk. Ceres was the most useful, but it only stores 10 ounces in the inner chamber, so bring both options of you're going to be out and about and prodice a lot
Emergency kit