In Croatia the national currency is the "Kuna". It is more or less linked to the Euro at a rate of 1 Euro = 7,3 Kuna. Everywhere you can find money machines that work with credit- or maestro cards. Of course you can also change money (Pound Sterling, Euro, or other) in any bank. In case you only dispose of Euro's, do not worry too much. In most places people will accept the Euro, using a very reasonable rate. After all you are only just outside the Euro zone.