Flight
The wedding is located in Northern Ireland, which is a part of the UK. There are two major major airports at which to arrive, Belfast International (Northern Ireland; this is the closer of the two) and Dublin Airport (Republic of Ireland). Fly to whichever airport is cheapest, though Dublin Airport tends to have the best deals. There is an open border between the North and the South, so no need to be concerned about driving/taking a bus up from Dublin.
Hotel
This is where the reception will be. You are encouraged to book a room here to spend the night of the wedding! Google Maps link: https://maps.app.goo.gl/Xo8qYuefUpApbjNt6?g_st=ac