www.highernature.com have lots of products that you can take just before and while you are on holiday. One of them is the naturally occuring bacteria found in yoghurt I believe, in capsule form so it doesn't have to be refridgerated. However, if you email them with this question, they will be able to tell you exactly what is recommended.
They are teamed by a bunch of qualified nutritionists and I use lots of products and vitimins from them. they are mail order too which makes them convenient.