I stopped at this site because I googled about my trip this summer. And now I'm here, hello. =)
Well, I will travel to London this summer. And I'm now thinking of spending three or four days in Ireland. I'm not very much interessted in the big city life (I will already see that in london ^^). No, in Ireland I would like to see mountains, green, coasts, old castles, grassland, foggy places and so on. (stereotype Ireland ;) )
I would also like to travel from london to ireland by train or ferry if possible.
I am very new to this board and also planning a trip to London and Ireland. I will leave the important question of where to spend your precious 4 days in Ireland to the very competant and knowlegable Michele as well as the other kind Ireland experts on this wonderful board, but as to the ferry question I will share what I have been advised by my family in London Fly. It is cheaper more pleasant and most importantly, with your limited time, it will give you more time to visit Ireland.
Welcome to the forum. I'm glad you found it through a search. As Suzanne suggested, flying will (in most cases) cost less and take a lot less time. I suggest you look into that option and weigh the differences in price and time.
Will you be traveling around Ireland by car or public transportation? That will make a big difference in what to see and do.
You will want to go to my "Transport" page for links to public transportation in Ireland. Trains hub out of Dublin and go like spokes to other areas of Ireland. Buses fill in the gaps. For instance, you can get a train from Dublin to Killarney or Galway but you cannot get a train from Killarney to Galway.
Choose places to base yourself that do day tours to various areas. This will depend on what time of year you go to Ireland. The tours do not run year-round.
Let us know if we can help when you have more info available.