In the US, refusing to give evidence (taking the fifth) can be used against you in a civil suit, but it cannot be used against you criminally. If you’re facing civil and criminal liability at the same time, this puts you in a tough situation, since protecting yourself from criminal liability might increase your civil exposure.
I believe in the UK refusing to give evidence might be worse, both because they have a whole different model of courts (inquisitive vs. adversarial), and because the underpinnings of US legal rights stem from a perceived short coming of the British court system.
Yes, the UK police caution is "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."
Our system of courts is at base very similar to the US, and is adversarial. The only significant parts which aren't are the coroner's courts which investigate deaths using an inquisitorial process.
[Edit: we also sometimes have public enquiries, sometimes headed by judges, but these aren't courts as such: there are no civil penalties or criminal punishments as a direct result of the enquiry]
Our procedural rights are mostly similar too (we have corrected most of the abuses since the 18th Century). Your right to silence is qualified, though, and has been since the 1990s. Basically, you can't remain silent during questioning and then run a 'surprise' defence: so if you're going to claim an alibi at trial, you can't wait until the trial has started to mention it. If you do, the magistrates or jury are allowed to draw adverse inferences from your earlier silence.
I don't much like this change. I don't know how much of a difference it makes in practice; there aren't ongoing campaigns by defence lawyers to have it overturned, for example.
I believe in the UK refusing to give evidence might be worse, both because they have a whole different model of courts (inquisitive vs. adversarial), and because the underpinnings of US legal rights stem from a perceived short coming of the British court system.