NHS-dedicated shopping times

Tesco
 NHS
 an hour ahead of normal opening times every Sunday

Sainsbury’s
 NHS and social care workers
 7.30am to 8am Monday to Saturday

Asda
 NHS priority in larger stores
 8am to 9am Monday, Wednesday and Friday

Morrisons
 NHS
 7am to 8am, every day except Sundays

M&S
 NHS exclusive access
 first trading hour Tuesday and Friday

Aldi
 NHS, police and fire service
 9.30am and 10am on Sundays
 8.30am and 9am in Scotland

Source
 https://news.sky.com/story/coronavirus-when-are-supermarkets-open-just-for-nhs-staff-and-elderly-customers-11962361