There are no import charges, as Norway is part of the European Economic Area, and Britain is a member of the EU, still(...). So free trade still applies, but he needs to declare an import. If he paid VAT in Norway he should be off the hook (EU again).
But "your results may vary": some countries may apply VAT or other taxes. In the Netherlands there is an extra tax on cars, which you have to pay on import. This ranges from 45,2% of the listed catalog price of a new car (so one pays the manufacturer's catalog price, 45,2% car tax plus 21% VAT...), and decreases to 0% when a car is 17,5 years old.
Erik Jostad is on this forum as well. I have not dealt with him personally, but what I heard about him is positive. He currently has three Dodges advertised on MilWeb, including a Canadian built APT:
http://www.milweb.net/webvert/90345. In his adverts Erik states he can arrange shipping and necessary export documents (needed for pre-1950 built and military vehicles). If the truck has a Norwegian title your friend should be able to register it at the DVLA without hassle (again thanks to the EU).
I would advise your friend have a look at the UK's DVLA and HM Customs websites, do some homework and go buy that truck!
HTH,
Hanno