ROI registered camper - How do I re-register it here?

[prophead]

It doubled as a removal van when we came back over to the UK and has been pretty much parked since we arrived due to getting settled and a busy work schedule.

Whats my first step? I know with my Irish registered car I have to, 1-insure 2-MOT and 3- tax (I think) but not so sure about the camper as in Ireland it was treat as a commercial vehicle for the test

Couple of pointers or links to the right spot on 't DVLA website would be greatly appreciated!