I don’t know about the UK as a whole, but London is not safe at all.
I wouldn’t call it inherently dangerous for the average person either, like some places in the world. But it was strange to go home last year and talk to the teenagers on my estate, who were now selling hard drugs, had stab/bullet wounds, easy access to guns and considered this the norm. All 16 years old or under.
It was never this bad previously. I hear from friends petty crime is rife, people riding scooters and bikes snatching phones with impunity.