Things I know about that are scary/interesting:
The UK has been accepting Russian money going through London for years making it an oligarchs playground. Is there any thing about our financial regulations that make easy for Russians to launch money in the UK.
The Russians have been killing people they don't like for years in the UK.
The police investigations have been surprisingly incompetent or inconclusive in some cases seeing as it is bloody obvious at least on the surface. Also the police have suffered serious cuts so maybe russians offing other Russians isn't a huge priority for them.
The NHS was targeted by cyber terrorists thought to be Russian a few months back
The eu was set up to help promote peace in Europe, which was previously dreadful for having wars. Putin would love nothing more than the eu to be weakened. Some of the leave side paid IT companies with Russian connections millions during their campaign.
I doubt the poisoning of stirpal (sp?) was done to provoke the UK more than he lived here and they gotten away it many times before. But russia is a bully and they know that the UK is a weak target. (Brexit, economy, self-serving government whose protection of the party is more important than its citizens).
It's all very interesting and scary. Buzzfeed has an excellent series of reports on Russian murders in the UK.
I doubt that I have reassured your fears. But in general no news is best for your mental health.