Fast forward to 2022.
Having informed DVLA about my MS diagnosis back in covid-lockdown-affected 2021, they got back to me a year later, rescinding my 10-year driving licence and I can expect to receive a replacement 3-year medical licence shortly.
Current policy is to take medical reports to determine ability to drive rather than retesting. A retest suggests an inability to follow the highway code rather than a physical impairment, so retesting won’t necessarily provide an answer to the right question.