This was a question quite frequently asked a few years ago when the Beach didn’t come as standard with EHU. Have a look through the Beach subsection of the forum and you will find the threads there. Couple of decisions you will have to make:
Where to place the external socket – Options are under bonnet, under rear bumper or where VW put it in the nearside panel (involves cutting!!).
Where to place the internal outlets – Nearside B pillar or back of seat plinth are usual places.
Where to put the circuit breaker/fused distribution box – Under passenger seat is usual. Some people have put it in the area above where the jack is stored I believe.
Most people also add a means of charging the leisure battery when on hookup. Often a ‘smart’ charger such as the CTEK ones.
As to costs a ‘hookup kit ‘ with sockets, cable & distribution RCD/MCB ~ £70
http://www.travelvolts.com/Mains-equipment.html (he also does fitting and gets good reviews)
Smart charger to charge the leisure battery ~ £100 I have this one
http://www.ctekchargers.co.uk/ctek-mxs-70.php
For the labour, depending on complexity, positioning, number of outlets etc could vary from a couple of hours labour to a day I expect. I ended up doing it myself and getting it checked by an electricial friend. I was putting it into a kitchen pod though so not a std installation. Did ask my local VW garage about retrofitting but they weren’t interested.
