Seen as though we were talking about this earlier, I saw these faqs on the arriva sailrail website
Which routes can I travel on?
Available for standard class travel from any station in the UK to and from Dublin via Holyhead.
Available for standard class travel from any station in the UK to and from Rosslare via Fishguard.
Available on all rail operatorsí services.
Please note: if you would like to travel from the UK to Belfast via Stranraer, please visit First ScotRailís website for further information.
Which Irish stations can I travel to?
SailRail tickets are available to most stations in Ireland.
Please note: for online sales, you can only purchase tickets to the following Irish Stations: Dublin Connolly, Dublin Ferry Port, Dublin Port Stena, Dun Laoghaire, Rosslare, Cork and Limerick. Other Irish stations will be available on the online booking system from May 2011.
If you wish to purchase SailRail tickets to other stations not listed above, please visit your nearest railway station.