If you have food-allergies or intolerances it can be difficult to travel, particularly if you travel to countries where they don’t speak much English. However, it is not impossible, you just have to prepare in advance.
Although you know they can offer glutenfree food, I would highly recommend to bring some glutenfree packed food like bread, crackers, biscuits etc… It can save your day if you are out sightseeing and don’t find anyhting to eat.
For lactoseintolerants it can be convenient to bring lactase, either in drops or tablets.
You can take a look in the pantry to see what I use to bring on my trips as a person following the low FODMAP-diet.