Mrs H from H,
Lots of people here have mentioned the schools available in Dublin. The CLUBS around there are a different breed altogether.
Personally, I would no longer bother with any of the clubs that are still based at DUB itself, given the crazy hoops you must jump through to get a general aviation flight airborne there now (24 hours PNR, endless holding on the ground, security issues etc.).
A couple of the clubs formerly based there have moved to Weston and provide excellent value and great aircraft availability and top-class instructors for check-rides etc. Try the Leinster Aero Club (who run a C150) or the Dublin Flying Club (they run an Arrow and PA28140)
http://www.geocities.com/dubflyer/ Though their website's a little out of date I'm afraid.
Weston is developing nicely at the moment and offers a good flying environment less than half an hour's drive from the city centre.
Gash