The best time for the UK to have become a federal state would have been 1707. The next best time would have been 1800. The next best the 1840s then the 1890s, then 1910s, 1920s, 1950s, 1970s, or 1990s. Yet every time it was raised it never got any traction.
So tell me again exactly why independence of the constituent nations isn't a good solution & should be opposed because a federal UK would be better option & solve all the significant democratic & constitutional problems.