This is strongly overstating the case:

The UK right to silence is pretty well summarised in the modern wording of the police caution: "You do not have to say anything. But it may harm your defence if you do not mention when questioned something which you later rely on in court. Anything you do say may be given in evidence."

Staying silent is not obstruction of justice or contempt of court. No one is ever required to respond to questioning. But it might lose you credibility in court of you produce an alibi or other defence at trial that you didn't mention during questioning.

The only exception is passwords and encryption keys, which have to be supplied if a court order is obtained and aren't considered testimony.