Thanks bbko for the advice.
In fact I did exactly that today.
I live near to the Transport Office near the Regents School, so I rode down to the 'DoR Ror Or' place where I get my Car Tested.
It is on the 36 not far from the Transport Office.
They took my motorbike log book and checked the bike as it is over 5 years old.
I bought their compulsory insurance and they said come back tomorrow to pick up the tax disc.
I have a receipt to hand to them tomorrow as they kept the log book.
It could not have been simpler.