From the Tesco website, Ringlet:
"We know that it’s difficult right now to get a delivery slot for online shopping. We’re at full capacity for the next few weeks, so if you’re able to shop in-store safely instead of booking a delivery, it would be a great help. This will allow us to start freeing up more slots for the more vulnerable.
We’re looking at every opportunity to increase the number of slots available. [i]As we increase our capacity, we’ll also set aside more of these slots for our most vulnerable customers[i]"
https://www.tesco.com/help/covid-19/?icid=dchp_c1_thinkb4click_wk5
From the Asda website:
"The UK Government has identified over a million people in England who have conditions that make them extremely vulnerable to coronavirus (COVID-19) and have advised them to self-isolate for 12 weeks to protect themselves. We have been working closely with the DEFRA and some of our fellow supermarkets for the last couple of weeks to understand how to ensure essentials reach those with no support network. The data we’ve received from the UK Government has allowed us to email our customers to offer first access to delivery slots, ensuring they get what they need while they stay safe at home. We’re also working on similar programmes for customers in Scotland, Wales and Northern Ireland."
https://www.asda.com/feeding-the-nation
I'm in the 'highly vulnerable' group (due to ongoing chemotherapy) but I'm still doing my own shopping. I'm simply limiting my shopping trips to one every two or three weeks and choosing to use only supermarkets where (through having wide aisles, etc) social distancing is easy to maintain. After three hours of chemo at Ipswich Hospital last Thursday, I drove straight to Waitrose (where they've got really wide aisles and only allow about 10 customers in the store at any one time) and did enough shopping to hopefully see me through the next few weeks.