The Cork Go Group had its beginnings in late 2003, when John, Ciarda, and Tong Yu met on UCC campus. Although individual games had certainly been played before in Cork, this was the first time regular meetups were discussed. Over the next few years, the group slowly grew to about a dozen members. There was a large overlap between the Cobh and Cork clubs, with John organising meetings for both in the early years and most Cobh players also travelling to play at the Cork meets.
Activity increased dramatically in 2006, during which the Cork club was lucky enough to have been joined or visited by several mid-level amateur players from the USA, Poland, and France. In August, CorkGo went online.
Early 2007 saw a regular turnout at weekly meetings, but Go locally took a big step forward when one player managed to get a regular club running in UCC that October. (Original site)
In January 2008, the UCC Club ran Cork’s first ever Go tournament. The one-day event drew a total of 18 participants.
The following year saw not one but two tournaments take place in UCC. This was due to the date being brought back from January to its now usual position of November. The duration was extended from one day to cover Saturday & Sunday.
In late 2009, UCC Go took an academic year out.
This led to the 2010 invasion of the Idle Hour pub by Cork Go players, exposing several local chess aficionados to the game.
Fortunately, during the second half of the year, new management shook fresh life into the UCC club and the annual tournament had its best turnout to date, despite the now-traditional disastrous weather. (2010 site.)
The next few years were unremarkable. Play continued in Cork, though numbers declined through 2015/2016, with tournaments for those two years having the smallest attendances ever. The Cobh Club was reduced to two active members for much of the 2011-2016 period.
The IGA is attempting to compile a more complete history of Go nationwide.
There is an article that attempts to trace the history of Go in Ireland from its fragmented beginnings up to ~2003.