We are very fortunate to have writing.ie in Ireland. The team who runs this website and agency is amazing. They have provided lists of Irish agents and publishers, which are updated as required.
Irish agents: http://www.writing.ie/resources/irish-agents/
Irish publishers: http://www.writing.ie/resources/irish-publishers/
Please do your research to find out which agents and publishers are interested in representing children's or young adult literature, and follow their guidelines for submission.
Best of luck!