Perhaps I am missing something but this link reports:
"The plans include action to boost early diagnosis and better patient and carer support. "
This does not imply everyone will get tested, even if it is in your familly. I would suggest it aims ,certainly initially, at diagnosing thse who have it. This is reinfored by the report that doctors dont recognise it.
Dementure is a terrible thing. My Mother in law has been diagnosed with Alzheimer's although apparently it is impossible to be 100% until you die and they look at the state of the brain. Of course she is oblivious but my Missus has a nightmare. Getting care plans are not easy either, you simply have to push push push. We were lucky that her doctor did recognoze it, the advantages of living in a high elderly population area I guess