We do not rely on the ECHR to protect our free speech. If we did the UK would no longer be a democracy. I'm offended by the suggestion that our democracy and society is so fragile that without them we would have no rights. Expect a police raid very soon.
We're talking on the order of a few hundred arrests per year for section 127 of the Communications Act and 1500 per year for the Malicious Communications Act, which includes stuff like racial harassment, domestic abuse, pedophilic grooming, and a whole host of things that I would hope you agree should be illegal.