It's a common response to bad times, to look back with fondness at previous leaders, and assume that, where they here now, things would be better.
It's highly unlikely.
For all her personal determination, Lady Thatcher was a pragmatic politician, and she would have seen the wisdom of signing into the ECHR legislation for the benefits she would have seen at the time.
We all have 20:20 hindsight, and wish things were different, but they aren't, and getting misty eyed about a politician who was once a powerful force, but became an intransigent liability, doesn't really help things.