Since the UK has National Health Service, do they sell health insurance?

No.

The NHS is single-provider health care, although we do have private hospitals and private health insurance for those hospitals.

In small quantities, they make the NHS even better.

Health insurance is what Canada and France have, Single-payer systems except that in both France and Canada there is “co-pay” just like in any insurance scheme.

• In France, if you pay social security taxes you get most of your health care insurance for free, and the rest of the hospital bill (for example) is a “nominal” charge. Probably to encourage you to not be sick.
• In Canada, they have a similar system set up for each province.

I have already answered questions from Americans about private health care providers and private health insurance.

BUPA and Nuffield are actually very good value for money. For example, Nuffield includes things like swimming pools and health club memberships, and regular checkups.

But the simple truth is that no one needs private health care providers. They just are more convenient for the people who have them AS WELL as the NHS.

And you really need to understand this part.

• If you get hit by a car on a public road, you get treated by an NHS A&E and get taken there by an NHS ambulance.
• If you have cancer, BUPA and Nuffield will have nothing to do with you.
• But maybe you can give birth in a much nicer place than the local NHS hospital. Maybe.
• Prince Phillip went first to a private health clinic when he was unwell. And then he got treated by the NHS like everyone else.
• And when Boris Johnson had covid, he was put on an NHS ventilator.

Please don’t get the idea that if you are rich enough to come to the UK and pay to go private that you will not get a service that is not “better” in some way.

But 90% of the time when you really need it you will be right next to me in A&E, and right next to the chap who stinks like he just shit his pants, because he just did.

Just like 90% of the time in US hospitals, except that I don’t pay anything.