Which airport are you flying from? You could see if they have boots and order a pot to collect when you get to the airport / air side. Maybe get some bottles for coming home, too.
Hot shot method (without nuby). Take out one flask of cooled boiled water, and one of boiling water. Plus make up the first bottle before you go out, but leave about 30ml short. Then add boiling water up to the desired level to warm it when needed.
Use the Nuby with water only so you don’t have to sterilise in between. 1 flask of boiling water, measure in your bottle the amount you need, pour into Nuby leaving roughly 1oz for hot shot, add the formula into bottle, cool the boiling water in the Nuby and add to the hot shot formula. What’s what we do now when out and about and will do the same for holiday 😊