I've figured out why normal people don't bother with Sail & Rail any more. Talk about a rigmarole booking a ticket. I went into Longford and spent 15 minutes waiting while the ticket agent finished up her phone call - I'm not exaggerating here. I gave up waiting at that stage and stormed off in a huff.
So then I tried the internet. It doesn't appear to be possible to book Stena at all on the internet and half of their ferries don't take foot passengers anyway. So I tried ringing them and they said that they just give you an open rail ticket for the journey but I would have preferred a seat booking so I gave up on that.
So I tried Irish Ferries who are by far the best of a bad lot. But when I wanted to book a club class ticket for the ferry, this is not possible on-line and it says to send them an email.
So after several emails which obviously weren't read on their side (they couldn't seem to get their head around the fact that I lived in Ireland and was booking a ticket from England), I did what I should have done in the first place and rang. This produced results and they were quite efficient in being able to lift the details off my email trail and I got a ticket booked.
The next thing I got an email confirming that I had booked a ferry ticket but no mention of a rail ticket, which resulted in yet another phone call where they said that this always happens and to just confirm the rail part of the journey when I got the ticket in the post.
In the course of this, I spent 5 minutes seeing what a flight would cost which would have resulted in a ticket costing about 2 euro less (including a checked bag) on Aer Lingus. So for flying, less money and a 5 minute booking process while Sail & Rail took me 3 phone calls, a few web sessions, 5 emails and a booking office visit.
It is a pity it is all so complicated - I am looking forward to the journey and figure that it is a much more civilised way to travel than flying.