Wow - you seem to be able to buy SailRail walk ups without going to a ticket office!
Yes this is indeed possible, and unlike other sites which can book SailRail it doesn't need to find an itinerary. This is particularly useful for things like Belfast to places which can't be reached in a day from the only bus-connected ferry to Cairnryan (the 07:30). In these cases a break of journey is permitted according to the Conditions of Travel, but the normal sites don't seem smart enough to handle this and refuse to see to these places. Similarly in the other direction too, although I'm not sure if Stena will accept a SailRail ticket that is dated for the previous day and for whicih an overnight break of journey was the only option.
A problem though - BR Fares is only issuing tickets on departure so this is no good from the Irish end. This is not made clear on BR Fares when clicking 'buy'. Instead it states "ToD" and "
Your tickets will need to be collected at a station before travel". This is a problem as (to the best of my knowledge) there is nowhere on the island of Ireland which can print a National Rail ticket (I think the last place was Stena Belfast terminal but they don't have a machine any more). So people will get confused by this and could turn up at an irish Rail or NI Railways or a ferry terminal and expect their ticket to be available. The wording needs to be changed - even better a postal option would be good. Even better again a QR code, but I will stop dreaming now!