British Imports

Try Lerøy Mat.  There's one of these in Bergen, and while it doesn't have everything you'd expect from a British supermarket, the selection is a that bit more familiar.

I don't know about Cadbury's, but Campbell's soup is my little luxury from Lerøy Mat.  Whoever thought you could miss tinned soup?

By the way, if you've just moved to Norway (which is what I've gathered from your questions about permits and the like) then I recommend you try to get familiar with Norwegian foods.  It sounds trivial, but it goes a long way in helping you integrate with Norwegian society (kvikklunsj is an institution), and expats who integrate tend to do better than those who don't (those who don't integrate tend to have a terrible experience and go home around the six month mark).

You don't have to like every Norwegian food, and you don't have to abandon those things you like from the UK, but it makes sense to dive in to the new tastes of a new country!