I wouldnt worry too much about the counrty youre going to. But think more on how you are feeling and what activities you are going to do. If you think you can handle the walks (are they long ones or short ones, will there be many toilet stops?) Also what about food, can you eat everything or have you got a strict diet?
It will be best if you talk to your teachers about it, after all im sure they have been there before on other school trips, so know what it is like. If you tell them of your disease and you may not feel like going on certain walks etc im sure they will be accomodating. Also they will be able to help with any special dietry requirements (ie making sure theres no sweetcorn on your plate).
It might be worth taking a bag with extra undies, jogging bottoms, toilet paper and wet wipes when you go for walks just incase. Also make sure your crohns is covered if its a group insurance, may be worth taking some out yourself (NACC website has a list of crohns happy insurers)
Dont go if you feel you wont be able to manage, but it would be a shame to miss out just cause you arent 100% sure ( i was going to cancel my trip to france this year as I wasnt feeling 100%, decided to go in the end and it was great, glad i did)
