Driving
It is about a 4-hour journey from Dublin to An Chúirt. If you are driving to An Chúirt take the road to to Letterkenny and then either take the N56 via Creeslough and Dunfanaghy, or if you want to see some fantastic scenery take the R251 via the mountains and Glenveagh National Park.
From Belfast it is a 2.5 hour drive to An Chúirt.
Bus from Dublin.
The world-famous John McGinley bus leaves Parnell Square in Dublin and takes you to Dunfanaghy, Falcarragh, and Gortahork along the way. It is €40 for a return ticket and you book online on their site. Depending on traffic the bus can take up to 4-4.5 hours (with a 15-minute pit stop in Monaghan). The bus leaves too late on the day of the wedding to make the ceremony on time. If you are traveling on the night before (5th), two buses are running that day, one leaving Parnell Square at 09:30, stopping at Dublin airport at 09:45, and arriving in Dunfanaghy at 13:35.
There is a later service leaving the city center at 17:45, stopping at the airport at 18:00, and arriving in Dunfanghy at 21:55.
Bus from Belfast
The Patrick Gallagher coach runs from Belfast (Jury's Inn) once a day at 17:30 arriving at Gortahork at 20:25. The bus back to Belfast departs Gortahork at 08:15 each morning.
Bus from Derry
There is one bus each way per day leaving Derry at 19:00 and leaving Gortahork at 08:15.
Internal Flights
There is a small local airport in this part of Donegal (Carrickfinn) that proudly boasts the world's most scenic landing! From Dublin Airport it is only a 30-minute flight and return flights go for €100. A taxi from the airport to Dunfanaghy would cost between €70-€80 and less to An Chúirt / Gortahork. Be warned if you are not a good flyer, it can be a bumpy landing and sometimes the flights are canceled due to bad weather, although this would be very unlikely to happen in September.
There are two flights into the airport each day, departing at 11:40 and at 18:50.
There is an Enterprise car hire service at the airport. Booking in advance is required. The office closes at 5pm so car rental is not possible for the later flight.
International Flights
From UK
Belfast International Airport is just under a 2.5-hour drive to Falcarragh so if you can get a direct flight to Belfast this might be a quicker option. There is an Easy jet flight from Gatwick to Belfast International as well as a Ryanair flight from Stansted.
Derry Airport is 1.5 hour drive to Falcarragh so this is the quickest option from London, although the costs of flights to this airport are much higher than Dublin and Belfast. Logan Air operates this flight.
Further Afield
If you are flying from further afield, then it will most likely mean flying into Dublin and either driving or getting the John McGinley bus to the area or getting the internal flight to Carrickfinn.