Western Ireland .... you are talking about serfboard munching waves....
You don't need to go with a kitesurf specific board. Most surfboards will do just fine.
Get your hands on a few dirt cheap used surfboards and muck around on them.
You will find that it will be a blessing to have "expendable" surf boards in the conditions you will be riding in.
An ultra tough board you may want to consider is the Spleene Zone. Its a classic surfboard outline
but in a very resiliant twintip construction.
Also look around for a used Aviso board. Sometimes you can get lucky and find a great deal.
These boards are expensive, but have great floatation and the best flex pattern there is for directional kiting becasue they are hollow. www.avisosurf.com