Sending off diplomats won't hurt Putin as much as sending off McMafia style oligarchs. Unfortunately UK has no guts to do it.
An the UK has no guts to do it because it collects rich crooks from all over the world to spend their money in London and prop up the UK economy.
The idea that they would put pressure on Putin is silly, it's the opposite, Russia in fact puts pressure on those who don't want to repatriate. That control of resources you are talking about can be a rather uncertain and fleeting leverage as many have painfully learned on their own example.
If Putin did what is alleged, we kind of know he's capable of this being that he can tell the rest of the govt what to do and has in effect extrajudicial powers.
The UK, it's expected, runs its government differently.
Isolating Russia killed it once, and the Russia of today is a shadow of its former self.
The UK doesn’t need Russia, long term, especially with the rise of China as an economic force.