@scb1: https://www.gov.uk/importing-vehicles-into-the-uk/temporary-imports
http://en.wikipedia.org/wiki/Domicile_(law)
Pracujesz, płacisz podatki = jesteś rezydentem = planujesz zostać.

@420SE: You can usually use a vehicle with non-UK number plates without needing to tax or register it in the UK if ALL of the following apply:

- you’re visiting and don’t plan to live here
- You only use the vehicle up to 6 months in a 12-month period (one single visit, or several shorter visits adding up to a 6-month period)