B&Q has reopened all of its stores across the country while another 20 Pret a Manger sandwich shops will open on Friday, as the number of businesses resuming trading continues to grow.

B&Q said all 288 of its UK shops were now open to the public, albeit with strict new safety measures in place. The DIY chain is classed as an essential retailer under the government’s high street lockdown rules, but it shut up shop in March before making a staged return with 155 stores last week.

B&Q has followed the example of supermarkets by limiting the number of customers in stores, switching to card-only payments and installing perspex screens at checkouts. Owing to the bulky nature of some DIY materials, the retailer is allowing two people to shop together so that they can “self-serve” larger items.

Rival chain Homebase is also returning to full strength. It currently has 70 of its 164 stores open, but said they would all be open by Saturday. The Homebase chief executive, Damian McGloughlin, said a lot of hard work had gone in to ensure it could “safely welcome customers back through our doors”.

Sign up to the daily Business Today email or follow Guardian Business on Twitter at @BusinessDesk

Pret a Manger said that on Friday, another 20 London stores would reopen to sell sandwiches and coffee as either takeaways or for delivery through apps such as Deliveroo and Just Eat. Stores will only open until 2pm, with the new wave of openings taking the number trading to 30.

Pret’s chief executive, Pano Christou, said the shops looked and felt a little different from before because of physical distancing measures: “I believe we’ve found a way to operate that reflects the government’s guidance and looks after our teams and customers,” he said. “We’ll keep on learning from these shops as we look to reopen more over the coming weeks.”

A growing band of fast-food companies including Nando’s, Burger King, KFC and Wagamama have also started to lift the shutters. Restaurants and pubs were closed as part of the lockdown but can prepare food in their kitchens for takeaway or delivery.