All you should need to do is fill in a customs carnet form. This is a document that shows that the device was purchased in your home country and that all duties were paid. It means that you can then temporarily "export" the device to another country and re-import it later without any further duties coming due in either country.

Simple really, contact HM Customs or any shipping agent for details.

Thoughts and information provided on this forum are mine and mine alone and do not necessarily reflect the policy of NSW Health. They may also be complete bollocks!!