I visited Europe back in 2000, and spent most of my time (12 days) in the Republic of Ireland. Vegetarian food wasn't hard to come by, but vegan food was harder. More than 2 decades later, it might be easier.
I googled a bit, and this is one of several websites that came up:
A forum community dedicated to vegetarian, vegans, and vegetable enthusiasts. Come join the discussion about agriculture, preparation, cooking, recipes, scales, reviews, accessories, classifieds, and more!