The body (NASP) being guided direct from the UK Government's driving agency (DVSA) has made clearer what's new because of anti-virus restrictions :
Driving test content remains the same. However, not all "key workers" will be necessarily be granted a Critical Worker driving test. At the moment, tests are being offered ONLY to front-line staff in  the NHS and  emergency services. As such, instructors should give lessons ONLY to these people and if they're near test standard. So :
A register of trainers for key workers will soon be available. It will allow instructors (like me) to display a certificate. Police officers, and the public, can then see the training is essential.
Instructors applying to be certified will have to complete a short online course and theory test on safe training protocols. They will also have to show they are training key workers.