Millions of last-minute Christmas shoppers are expected to spend £3bn over what has been called Super Weekend, with retailers eager to make up lost ground after a “shaky start” to the festive sales season.

With many offices closing on Friday for the holidays, retailers anticipate the remaining shopping days will be among the biggest of the year.

Saturday is likely to be the busiest of the weekend days, according to an analysis by the discount website VoucherCodes. It estimates just over £3bn will be spent at the weekend, with 39.3 million people expected to head to stores or shop online. “A lot of people are leaving their shopping until later this year,” said Anita Naik, the website’s savings expert.

About half of Britons have not done their gift shopping yet due to the big day falling midweek, according to a poll for Gateshead’s Metrocentre mall.

Katie Wyle, the head of shopping centre management UK at Unibail-Rodamco-Westfield, the owner of the Westfield shopping centres in London, said: “Super Weekend is always one of the busiest calendar moments for retail, and at Westfield London and Westfield Stratford City last year we welcomed 550,000 visitors looking to maximise the final shopping weekend before Christmas.”

For those who have left everything to the last minute, the “good news” is that a few online retailers are taking orders as late as 24 December in time for Christmas, said David Jinks, the head of consumer research at the parcel delivery aggregator ParcelHero. “Amazon, Argos and a number of other stores are taking same-day orders on Christmas Eve … for a price.”

The final two months of the year account for more than a fifth of retail sales, making it a period of vital importance, particularly for clothing and toy retailers.

Sales were weaker than expected in November despite a welter of early Black Friday price cuts. Clothing sales were down as the milder weather meant people delayed purchasing winter coats and jumpers. Given this “shaky start”, retailers would hope “shoppers come out in force in the final days”, said Kris Hamer, the director of insight at the British Retail Consortium.

Going into December, toy sales were about 5% below 2023 levels, according to Circana. Melissa Symonds, the executive director of UK toys at the data company, said the picture would probably improve during the last-minute rush but it was likely sales would be down this year. Toy sales surged 17% over Black Friday “with everything building to this weekend and the Monday and Tuesday before Christmas itself”, she said.

The combination of higher energy bills and low consumer confidence meant it was a “cautious Christmas” for consumers, said Diane Wehrle, the founder of Rendle Intelligence and Insights, with the number of people visiting stores in the first two weeks of December down on last year.

“Shoppers are clearly leaving it late, and therefore it’s likely that many will venture out on Saturday to purchase gifts, particularly as a number of retailers have gone into sale already so they will benefit from discounts,” she said.

Some London tourist spots are facing industrial action on Saturday which could bring a different kind of crowd to Knightsbridge.

More than 350 workers including shop and restaurant staff at Harrods department, and security guards at the Natural History Museum, Science Museum and the Victoria and Albert Museum as well as at the Department for Education, will be involved in strikes and demonstrations.

Some Harrods workers will also be on strike on Sunday. The store has said it has contingency plans in place over Christmas to ensure its services are not disrupted by the planned action.