Holiday visa to Ireland was granted recently for TGF. It's a single entry Visa. Ireland is not a Schengen country. Can we go to different European countries or is she stuck and can't leave until visa expires?

OK here's one for the group, hoping to bring the wife over to N.Ireland next year, N. Ireland is the UK so a UK visa is required. Best flights are Bkk to Dublin but Dublin is Ireland, Irish visa required? Anyone done this recently. Dublin flights are cheaper, only one stop, and no connecting flight to Belfast required. Dublin to Belfast by bus direct.