The details given on the Cardiff thread have it only operating for 2 months in September and October. That's a period when the rugby world cup is on and Ireland have at least 2 matches in Cardiff, with probably a 3rd should they qualify from the group.
That said, it seems to start 2 weeks before the world cup, and operate on weekends when Ireland won't be playing in Cardiff, so it may be a case of watch this space.