The most up-to-date information from Norwegian authorities can be found on the Norwegian government's website, where you can read more about what Brexit means for UK citizens in Norway (external website) and about Norway and Brexit (external website) (in Norwegian language only).
The UDI does not have any other information than the one you can find on the government website. As soon as the situation is clear, we will publish information on our website.
As long as the UK is still a member of the EU, the rules for UK citizens who visit, live in and work in Norway will remain the same as before. They can use the registration scheme for EU/EEA nationals, and they can apply for permanent right of residence if they have lived here for at least five years.