lucyfretwell, Regina cherry is being grown here in NY to larger size that other sweet cherries. Regina originates from Germany as well as the dwarfing rootstock Gisela 5. Keepers in England may be the largest fruit tree nursery in the world. Their website shows only a few dwarf cherry trees unsold. Most sweet cherries need two varieties to set fruit well. Select cherry, gisela 5 , dessert and you will get the list that is available. I'd print the list as those varieties will probably grow OK in Ireland.

Here is a link that might be useful: Keepers Nursery