The status of the 'Turkish Republic of Northern Cyprus' is very much a grey area. For example, the EU regards the whole of Cyprus as being within the EU but, if you travel back from Northern Cyprus to the UK, you're only entitled to bring back tobacco and alcohol up to the limits which apply to non-EU countries. (That's because tax hasn't been paid to an administration which is recognised by the EU).
However, Northern Cyprus doesn't require EU citizens (staying for up to 90 days) to hold a visa. As far as I know, they also don't place any restrictions on passport validity:
http://www.cypnet.co.uk/ncyprus/tourism/touris t.html
Chris