Welcome to the site.
I've actually only ever visited Ireland by sail the once ant that was to Cork / Crosshaven further south. All I can say is you'll enjoy your time over there.
Suggest for marina recommendations and prices then searching the web, or securing a copy of Irish Pilot Books
like this one
East And North Coasts Of Ireland Sailing Directions: Marinestore Chandlers
FWIW its not always neccessary to use a marina at night - we've spent a few nights tied up off a pub jetty up a river - absolutely incapable of taking the boat anywhere else until the following day!
Enjoy your cruise