I think the main issue is UK won’t accept they’ll be treated like everybody else in the union. There is still an expectation of privilege that is severely misplaced in the context of what has been going on.

If none of this was an issue, I am sure EU would be happy to quickly let them rejoin. Having the UK in the EU strengthens Europe’s position, they have shown to defend Democratic values in Ukraine and, once they’ve come to grips with the end of their exceptionalism on the world stage, they’ll be a valuable asset in the world’s attempts to progress.

Coming to grips with that as a nation will be painful though, so I expect it to take a while unless something drastic happens.