The privileges of the licence are as defined in Schedule 8. JAR-FCL is not law and only has legal status where it has been specifically enacted by the ANO.
The privilege to fly a Microlight on the basis of a UK or UK issued JAA pilots licence holding a SEP class rating is valid anywhere in the World, in a UK registered aircraft as it is an ICAO licence. Another State may of course refuse to accept a permitted aircraft but they cannot refuse the licence if they accept the aircraft.