Here is the information on the NHS website.
digital.nhs.uk/.../opting-out-of-sharing-your... and a bit more here www.opendemocracy.net/.../matt-hancock-has.../
People are right to do more research. Sadly so many dismiss it out of hand immediately as “this must be wrong” is a huge part of the problem. Bad things happen when good people do nothing etc.
Opting out of sharing your confidential patient information - NHS Digital
Limericks with very strict rules (7) 88558