Be aware that National Irish Bank don't pay commission to brokers so as well as approaching a broker, you should also check out their offerings yourself.
There are a good number of brokers in the cork region that deal with most of the lenders. If you want to confirm this information - log on to the financial regulators website and check out all the mortgage brokers - it lists each brokerage and the agencies they hold. For example, if you look at my company, you will see that we hold 15 agencies.
I used REA and think they are good - they are the only broker to publish figures showing what percentage of their business goes to what banks. (No affiliation with company)