I am not a lawyer.
But I did once work at the BBC, where a very helpful woman once came round and explained to us the basics of UK libel law.
To be libelled in English law, you have to have a) something written about you which is b) untrue c) may cause serious harm to your reputation and is not d) an honestly-held opinion or e) a matter of public interest (this last defence is a new one).
The Defamation Act 2013 is available on the UK Government website. It’s short, and very easy to read.
I urge you to have a read of it before threatening to sue anyone for libel. Especially if the things you’re threatening to sue them for are b) true c) cause little harm to your reputation and are d) honestly-held opinions.
Because, otherwise, you come across as a bit of a dick.