Just a few things to consider.
Property in Ireland isn't particularly cheap. It's cheaper than it was, but that's only because it went absolutely crazy in the boom. My parents paid IR£19,000 for their house in 1979 and in 2007 the identical (three bedroom semi-d) house next door was on the market for 360,000 euros! Madness. It sold recently for 200,000, so a lot cheaper but still not cheap for a 3 bed in an obscure part of a small town.
You won't get a medical card unless you're on the dole. Which means every trip to the GP will cost 60euros and you'll pay full price for prescriptions. Some antibiotics cost 75euros or more.
Schooling is more expensive. No school dinners. You have to buy each child a stack of textbooks at the start of each school year, along with all the pencils, pens, art supplies and copy books that they need.
Schooling is just about guaranteed to be Catholic. Not a problem as long as you don't mind a very religiously informed education.
You can't switch passports anymore. Due to the EU your passport is valid and remains valid throughout your life.
My teacher friends can't get jobs.
Cost of living is considerably higher in Ireland - you will pay quite a bit more for food, clothes, cars etc.
Despite speaking the same language and having something of a shared history there are definite cultural differences between England and Ireland that might surprise you. Be prepared to feel a bit of a fish out of water for a while.
I don't say all this to put you off - I moved from Ireland to England and I am delighted I did it, it's been great. It's just better to go into it with your eyes fully open.