There are different opinions about driving licenses when you live in Crete on a permenant basis. Some say that a currently issued Driving License is OK and if you have an old license without photograph, just carry you passport aswell. The DVLA in Swansea will only issue a UK driving license to someone with a permanent UK address, this then becomes a bit of an issue.
There is a process in Crete where by you can change your driving license, to a Greek license, you need to fill in forms, get your license translated into Greek, and make some declarations.
This is an extract from the official documentation at the British Embassy in Athens.
Under EC Directive 80/1263/EEC, the holder of a driving license issued in a member state of the EU (unless the license bears an indication that it was granted in exchange for a non-EU license) has the right to exchange it for a license of the new country of residence without taking a driving test. The application must be made within one year of taking up residence in a different member state; the previous license must be surrendered to the licensing authority. EU Directive 91/439/EU (implemented in Greece on 01/01/97) states that such a change for persons holding the EU pink common-format Driving License is not obligatory. A Greek driving license remains valid until the holder reaches the age of 65 years, after which an application for extension is required.