I do not have celiac disease, but a young doctor told me that it is more prevalent in Ireland than almost anywhere else, so appropriate food is quite readily available. If you Google 'celiac Ireland' you will find a good number of websites and lists to explore. Once you get to Ireland, you can download the Just Eat app which lets you sort restaurants by various criteria.
Most supermarkets have a 'saor'/'-free' aisle, where you will find gluten-free snacks and food that you could prepare in a self-catering apartment. I love Cornucopia (19/20 Wicklow Street, Dublin, Dublin 2), a vegetarian/vegan restaurant where all the dishes are marked as being glutenfree, vegan, soyfree, etc. It's right in the main shopping area, the prices are good, and the servings are generous. I often eat there because I like the food, and all my friends can find something to eat!
If you are traveling in the stunningly beautiful but sparsely populated Northwest, you may want to be sure you have appropriate snacks with you, but you should have no trouble in larger towns and university towns.
I don't think dietary issues will be a problem in Ireland. Enjoy your trip!