Aeroplane trip (snacks and milk)?

hi im going on a very long trip qld to london with my near 2 year old, she drinks a bottle of cows milk before she sleeps and sometimes a little bit in the morning she has gone off the toddler formula which i used to give her of a night as the vitamins were good as she doesnt eat very much has improved heaps though. as i can not take cold cows milk with me as the keep it cold thing i was thinking of giving her from 6 months S26 formula onthe box the guide lines say on how many feeds a day from 6 to 24 months may be more like milk than the toddler one what do you think, please also what snack ideas can you give me thanks a lot