I've lived here in paddyland all my life and believe me Ireland is snake free, except for pet snakes and politicians. Iceland, new Zealand, Greenland and Antarctica are the only other major countries in the world that don't have snakes. The only terrestrial reptile native to Ireland is the common or viviparious lizard.
It is only a rumor. Snakes can be found in the bushy and forest areas. You will not find the snakes in the resident areas. There are snakes in in Ireland. So be careful about that.