You can ordered a click and collect of formula to boots at airport so it not part of your travel allowance
Premade bottles will weigh loads, take formula… although at 1 could also be on cows milk then?
She will literally have just turned one by a couple of days so don’t know whether it’s best to just stick to what we know for the holiday?
We went when my baby was just turning 4 months. It’s actually a lot easier than I thought it would have been! We used the rapid cool and made up all bottles to the hot shot method when needed. Buy bottled water from the supermarket with a low sodium content. We used ready made bottles for journey to and from if the hot water in the flask was no longer hot enough to make bottles with! Hope that helps!