Why not allow the person who's data it is decide what can be given and to who. A memory stick, even an ID Card with secure encryption could be used and then it is up to the individual if they give it to a doctor or other individual.

You can then decide what parts of the information you hold on yourself is available to whom.

Mind you the ID Cards data would be maintained by the owner and NOT the government or any other body, with copy protection such that it was view only unless otherwise agreed. This of course would entail giving every household in Britain a free computer and other hardware to maintain for themselves.