Getting your car roadworthy won't be all that expensive. It's a matter of adjusting the headlights/headlamps to focus to the right, rather than the left (a manual adjustment that needs no equipment), you might have to get a rear foglight/foglamp (a simple addition that just tacks on) and something done to the side reflecters (sorry, I can't be more specific). At least these were the three things my 1993 Miata needed to change over, and once done, I passed every MOT/annual inspection since 1998.
If your car is a new one, chances are it might just need the headlights adjusting.
But to know for sure the costs and whatfors specific to the VW...I don't. Just my own experience. I think mine were less than £100. Oh, and, they won't make you change the steering wheel to the other side.
I know you already have an idea of what might need to be changed, but in case you haven't run across the standard MOT, this link lists the things that are checked during a UK inspection:
http://www.ukmot.com/mot_check.aspAs far as who can do the changes, any VW dealership in the UK that has a service department. Just locate the one nearest to where you will be moving.