I'm skeptical this goes anywhere legally speaking. The categorisation regulations are a statutory instrument rather than primary legislation, so they _are_ open to judicial review. But the Wikimedia foundation haven't presented an argument as to why the regulations are unlawful, just an argument for why they disagree with them. It should be noted that even if they succeed (which seems a long shot), this wouldn't affe…
More detail: https://medium.com/wikimedia-policy/wikipedias-nonprofit-hos... It seems to be a fairly standard judicial review: if OFCOM(?) class them as "category 1", they are under a very serious burden, so they want the categorization decision reviewed in court.
Very interested how this goes.