For legal reasons I like to keep discussions of particular breeders off the board.
In general, there are no lists though it would sure be useful) -- you need to actually ring the breed club secretary listed on the IKC site to find out who has litters coming up. I'd ask her for breeders who follow the heart protocols and cardiac test. You should try the secretary of the Northern Irish club as well.
I have a lot of advice for finding a puppy in Ireland in the puppies section of my rescue site:
http://rescue.cavaliertalk.com
Almost no Irish breeders have websites so it is hard to get such info in any convenient way, and sadly, very few that I have come across do even the most basic cardiac testing, much less testing patellas, hips and eyes. Hence it is a good idea to ask the breed club secretary for breeders that she knows actually do the proper health testing. Many will have some excuse for why they don't test, but the reality is that the heart protocol has been in existence for a decade, is known to help eradicate early onset MVD, and any breeder not following the protocol is not much of a guardian for this breed's health (improving the breed is of course supposed to be one of the goals of a good breeder).
In the UK, the main vet advising the UK CKCS club on heart health has argued the CKCS club really must start requiring cardiac testing as their lack of following the protocol has caused no change at all in the incidence of MVD in 15 years, when incidence should have noticeably dropped.
So this isn't just an Irish problem -- many registered breeders in the UK and US also do not heart test or only vaguely stick to the heart protocols.
Here's the UK vet's recommendations:
http://www.thecavalierclub.co.uk/health/hearts/proposal06.html
It will be interesting to see if they follow his advice.