> Is there a UK version of the EFF that fights in the courts against this lunacy or does it not quite work the same in the UK as it does in the US.

The government looks likely to introduce the ban as regulation through secondary legislation (https://www.bbc.co.uk/news/articles/c9824zvpz9po).

That is open to judicial review.

If primary legislation was instead passed, that's a lot harder to challenge - Parliament makes the law, so whatever Parliament said applies.

Politics is very different in the UK than in the US, especially when the governing party has such a large majority.

The banning of under-16s from social media has widespread support across the parties in Parliament.