I would agree with ClubMan. With BOI Cirrus charges are 3.5% ( min charge of €2.54 max €17.50) when used outside the eurozone.
I would recommend preloading your Cr Card but make sure you are registered for online banking before you go so you can keep an eye on your a/c's. Instead of putting one large lump sum into your CC I would drip-feed it in online as needed.
Also make sure you bring the banks emergency phone no's with you in case your cards are stolen etc. Your bank should have a little card with these no's that you can put with your travel documents.