Got this today from my AME.
The CAA medical department issued new exemptions, today 24 March 2020, for Class 1 and Class 3 medical certificate holders and Cabin Crew medical reports.
If you have a Cl1 or Cl3 certificate, or a Cabin Crew Medical Report which was valid on 23/03/2020 and which is not valid beyond 31/10/2020 then you may claim an exemption until 22/11/2020. In order to continue to fly, or control after 22/11/2020 you must re-validate with your AME before that date.
Carry your expired medical certificate and a copy of the exemption notice. We think a print of this email will suffice.
You do not have to claim the exemption - if you prefer to attend and maintain validity in the usual way we expect to remain here to provide a service, unless events dictate a change in this intention.
Importantly, if you have a medical condition that requires you to send in reports from a specialist then this must still occur.
If you are unsure please contact your usual AME and we will try to help.