I've looked into this a bit as I'm leaving Aus soon and heading for the UK via Africa. The UK Customs website doesn't talk about residency but whether someone is 'established' outside the EU. I couldn't find any clear definition of what this actually means.
If they decide someone is established outside the EU and allow you to temporarily import (and not pay duty) the maximum time they will let the vehicle stay is 6 months. I could be wrong, but it looked like when the 6 months is up the vehicle would have to be exported outside of the EU and couldn't then be transferred to a permanent import.
I guess things may work differently in practice between the UK and Germany, as you'll be able to drive into Germany without anyone stopping you but coming off a ferry into the UK the paperwork will be difficult to avoid.
|