I've done a lot of traveling with my ostomy. I live in the US and did a two week tour of Italy. Fantastic, by the way! I always took nearly twice the appliances that I needed. I have to cut the hole in the wafer so I did that ahead of time. Be sure to put your appliances, paste, etc. in your carry-on bag. You definitely don't want them lost and they are sensitive to heat, too.
I always rinse out my pouch after emptying it so I always carry a 1/2 pint bottle of water in my purse. I do this even when I'm not traveling. This gives you enough water to add a little to the pouch, swish it around and then empty it. Much of the output slides out easier. Then I add the remaining water to the pouch and that gets the rest of the residue out. Then I refill the bottle at the sink.
Other than that, I had no problems. I didn't even have to change the frequency that I needed to change my appliance. I would get up extra early on the day I needed to change the appliance and was done and out of the bathroom before my roommate even woke up.
I also carried plastic bags to put the used appliance in and that help prevented odor. Plus I carried paper lunch bags to put the plastic bag with the used appliance in so it wasn't offensive to my roommate. She couldn't see anything except a lunch bag in the garbage.
I absolutely loved Rome! I'm jealous! You will have a wonderful time and see all that you are learned about in school. Enjoy yourself! Oh, I almost forgot! They charge you to use the bathroom. Yep! So carry change...euros. They call it "pay to pee". And, many of the bathrooms are co-ed. Men and women use them so be sure to read the name on the door.
I also went to Walmart and got travel toilet paper and carried that with me, too. I'm not sure what store is like Walmart in the UK. The travel toilet paper is a small roll of toilet paper in a plastic container. Any store that carries travel supplies...things like plastic bottles, soap containers, travel size shampoo, etc....usually carry the toilet paper. If you can't find any, I'd put some toilet paper in small plastic bags and carry a couple with me each day. You may never need it but you sure would hate to be without it.
Sherrine