Being in the construction industry but working in the uk there are many good builders in cork now at very competitive prices.
What you need to realise if you employ a block layer and are not happy with his work you will have to pay for the blocks mortar etc if it's wrong, if a builder does it he pays.
Secondly you can build a lot quicker with a builder and get watertight then get your own tradesmen in to do the finishes inside, ie build the shell, roof windows and doors externally then get your own elecs, plastering internal doors etc done afterwards at your own pace.
Just an option that would give you a habitable house quickly with minimal risk.
As for a QS I couldn't help but have had a couple of builders quote me that used a QS to price my build. Can your architect not recommend anyone?
Good luck with you build.
Charlie