Again, the racism in the UK and elsewhere is one problem, Putin’s misinformation campaigns are another. These are two different things. (And, again, not all are racist in the UK - or in any country - as we can see, for example, with the ‘Rwanda deal’ you mentioned as this very deal is history now.)
That’s a too simplified abstract of what the article is about. It’s not that Russia made the racist far-right in Western Europe and elsewhere (the Putin regime appears to provide some funding to European right-wing parties, though, as we have seen in Germany’s AfD, for example), it’s that Putin fuels that sentiment. The Russian government tries to actively destabilize the societies, that alone is a violent act and by many considered an act of war.
(And, no, Britain is not “racist AF”, some people over there are racist. We should not pidgeonhole a country, neither Britain nor Russia.)
What has the police’s reaction here to do with Russia’s disinformation? It’s just about raising a new issue to point the finger to anywhere else.