I believe the 6 month rule applies to vehicles fully registered, insured and MOTed (or equivalent if necessary) abroad.
If you bring any other vehicle into the UK (which seems to be your circumstances), you will need an MOT (on the chassis number) then register it with your local DVLA registration office, who usually want to see the VIN plates etc to be sure it is genuine. They will then issue you a UK reg number and you can then tax it.
You may drive any imported vehicle from the port of entry to a place of storage or your home address and then to the testing station and back (then reg office) only. It must be insured and roadworthy even if it has no MOT. More than this is not allowed.
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This link appeared on another post recently and is one way of checking your paperwork is good, although not 100%.
I have only brought a new vehicle into the country so others may come along with more/different who have brought an older VW in.
