[TimeForThis]

Aside from not having a car (don't need one in London), I'm usually going over for only a couple of days so it's not worth using up a full day for travelling and then being really tired from the drive when I get there and when I get back. You have to take in the price of petrol as well as the ferry, which stops it from being in any way cheaper and it's already not stress free. The ferry costs about £300 for one person travelling with a medium sized car, no roof rack, with no reserved seating. That's about 3 times as much as a flight and you'll have had to drive for half a day to get there.

If I got a train from London to Holyhead, then a ferry to Dublin, it's 8h 30m and about £40 and then I'm left in Dublin port to find a way home with my luggage. Transport within Dublin is pretty crappy so we avoid it when we're over there as we are normally running around visiting family and friends. So it's slightly cheaper but still half a day's travelling and a bit hassle once you arrive.

We fly and pick up a car at the airport - much shorter journey, much cheaper than a ferry, probably not that much difference in price from the train but easy to do and we can pretty much relax (aside from airport security) rather than drive for half a day.