http://www.dublinbus.ie has the detailed info, seems to be pretty frequent service, just under an hour to Pearse St terminus.

Hi There

I grew up in Lucan and to be honest it is not really somewhere you would go on a break...there is nothing wrong with it it is just highly and densly residential.

If it is a city break you are after for a couple ie: not bringing kids, then you would be better off staying in Dublin City Centre.

If you stay in Lucan, there is no rail link into the city and a bus will take anything from 45 mins to 2 hours to get into the city depending on the time of day, if it is rush hour, Lucan is a bottleneck and you will be stuck in traffic.

What kind of a break in Ireland are you after and I might be able to recommend somewhere else to you.

Hope this helps you
Aromamum