This may not be a lot of use especially if one doesn't have a lot of time so I'm posting it on the offchance it may be of interest/help. (I'm aware that Dublin to London is faster the traditional route via Dublin/Dún Laoghaire).
Unlike Holyhead, Rosslare offers an overnight service in the continuous sense each way seven days a week i.e. no prolonged wait of circa four hours for the train. Just a short wait of around half an hour from the time one disembarks the ship (Stena) to the time the train can be boarded.
A through ticket from Connolly to London via Rosslare can be purchased but as most readers of this forum probably know few trains actually connect to/from the ferries. The major disbenefit is getting from Dublin to Rosslare. The last train to connect with the 2115 sailing is the 1330 ex Connolly (not an option unless one wants to enjoy a long meal/few hours in a Rosslare pub/hotel). One could though take the 1630 Connolly to Wexford train (arr. Wexford 1904) and catch a Bus Éireann coach immediately outside the station to the steps of Rosslare ferry terminal. Coaches at 1920 and 2010. Journey scheduled to take 30 mins but in practice is achieved in several minutes less (coincidentally same coaches depart from Busáras at 1630 and 1730 respectively). Dublin-Rosslare Harbour 16.65 e single online. Wexford-Rosslare Harbour 5 euro single onboard.
There is a cafe in the terminal and the Stena Europe usually commences boarding around 2015. The onward train leaves Fishguard at 0150 (but available to board before half one). At Swansea it's necessary to change onto a First Great Western High Speed Train which will be open and ready to board at an adjoining platform. Arrival at Paddington is 0732.
If one left Dublin by coach at 1730 the overall journey via Rosslare is only about an hour longer than via Holyhead and more comfortable as there's no prolonged waiting around.
(The return is at 2015 ex Paddington, arriving Rosslare Harbour 0615 and Dublin train at 0750).
Last edited by Traincustomer : 08-03-2011 at 22:31.