It's a mistake to take things like trial by jury, open justice ( not secret courts ), non-arbitrary detention, even regular elections for granted.
I totally agree with you that the UK is not Iran and there is too much hyperbole - but at the same time the current government is trying to criminalise legitimate protest, cancelling elections and trying to remove trial by jury for a substantial set of things ( the ultimate protection against an authoritarian state ).
As an example, it's very telling that the government ensured that in all the Assange legal proceedings it never went before a jury.
The current government creating all these precedents, in the shadow of the prospect of a potential Reform government is something I think we should all be concerned about.