It is worthwhile checking that following the recent accession of Croatia to the EU on 1 July 2013, that any Croatian national who wishes to work for you in the UK will need permission to do so, unless they are exempt from this requirement.
Please check the documents published on the UKBA website:
Guidance for employers on preventing illegal working in the UK: Croatian nationals; and
Code of practice for employer civil penalties: Illegal employment of a Croatian national