Otherwise, the advantage of the train is that it is a simple change in Cork train station, albeit with around half an hour between the trains.
You could also take the train to Cork and then a bus to Dublin, with about a 10 minute walk between the two. There is a wait of around 30 minutes for a GoBE bus or an hour for an Aircoach bus.
We will not have a car so parking is non-issue. Do you know where I can lookup prices for train tickets?
Your best bet is to book online in advance as fares will be cheaper. The price will be displayed on the website. If you are booking beyond the end of the period currently on sale, you could just try a date 6 weeks or so from now as a sample booking and that is likely to be as cheap as it gets.
Because they are expensive, I wouldn't recommend a walk-up fare, but if you want to check the price, they can be looked up here
Irish Rail web fares here, shown as single/one-way price, when booked online and in advance (up to 90 days ahead of date of travel, ordinarily):
THank you everyone! I checked the site and it does say luggage is allowed - does this include a checked bag for Airplane sized luggage as well?
There is no checked baggage. You can bring what you can carry yourself eg a large bag and a small bag.
That’s fine. I’m just asking if a larger bag, i.e. one that you would normally check on an airplane can fit on the train?
You’ll be using 2 very different trains.
From Cork to Dublin, you can either put large luggage between the seats where they are back to back, or you can use a rack at the end of the carriage. As you’ll be getting on at the first station and will have some time to kill, you can just board early and get a suitable spot first.