Health records have been held in electronic form for YEARS in the UK. Lloyd George envelopes are so 1980's The only difference is that they are held locally (at the surgery or in a data centre) and only accessible to that practice. What you are talking about are the various national shared record initiatives where a sub-set of the record is sent to a central location and can be accessed by other care providers.(e.g A&E staff).
In England if patient dissents from the programme (by having an appropriate Read code added to their record) then when the upload is done all that is sent is a note to the effect that they do not want a record. The NHS IT folk check that the system does this that there is no way any any information from a dissenting patient is sent up. I know I've sat through enough SCR witness testing sessions to last a lifetime. Access at the other end is audited and if necessary an alert is sent to the local Caldicott Guardian (not an end-of-level boss but a senior clinician with responsibility for protecting patient information).
There are a number of national programmes in the UK for centrally sharing part of the record. In England there is the Summary Care Record programme (data sent ranges from nothing to Allergies and time-bounded medication to the previous list plus any items you agree with your GP that can be shared). In Scotland there is the ECS Emergency Care Summary to support out-of-hours care, In Wales and Northern Ireland there is the ECR Emergency Care Record for use in A&E,