usually the place to start is to locate a birth cert for one of the children to establish the mother's maiden name. I had a quick look at the BMD index but as far as I can see there a number of possible matches for each of the children - so nothing certain yet. You could have to order a few certs to make sure you ended up with the right one.
Once you find a correct birth cert the next step is to search for a marriage. Sometimes this is possible using just the husbands name and the wife's first name and checking to matching index references - but again this did not show up a cross match due to the number of possible matches. I'll have another search tomorrow.
The other option is the (free) parish records on
www.irishgenealogy.ie (more RC records are due to be added later this year)
see :
Introduction to Irish RecordsShane