The leader of the UK’s biggest farming organisation says she is optimistic that British workers will come forward to rescue the harvest and keep the nation fed, instead of having to rely on flying in overseas workers.

“A lot of signs are optimistic and we have really positive news,” said Minette Batters, president of the National Farmers’ Union. “We are hearing people are very keen [to work on farms]. There does seem to be a real swell of support from people to do this.”

She said workers who had been furloughed were allowed to top up their income through farm work, and many others who had lost their jobs would see it as a lifeline, as well as a way to help the country through the coronavirus crisis.

Workers have been flown in this week on charter flights from Romania, despite travel restrictions and fears for their health and safety. Germany has also been recruiting farm workers by air from eastern Europe. About 80,000 workers are likely to be needed this year, leading to calls for a “land army” of paid workers to join farms.

Batters said there was still time for more people to sign up, as the critical period for the UK’s harvest would not begin until next month. “We will know much more when we get to May,” she said.

However, even if the labour shortages are less severe than some have predicted, farmers across the country are still facing a struggle to stay in business as their supply chains have been turned upside down by the coronavirus crisis.

For farmers, the biggest single problem is that before the lockdown about half of the food consumed in the UK was eaten outside the home, in cafes, restaurants and pubs. Now they are closed, supermarkets are struggling to keep up with demand for grocery shopping, but farmers used to supplying the catering trade have few ways of getting their produce to consumers. “It is very difficult, if not impossible, to switch,” said Batters.

Food must meet different standards when sold through supermarkets, and adapting the supply chain takes longer than farmers have to sell their perishable produce. “If you’re a potato farmer, and you sold to fish and chip shops, you can’t just start selling your produce direct. You can sell some at the end of the farm drive, but that’s only going to make a small difference,” said Batters.

Ministers have been slow to act, said Martin Lines, chair of the Nature Friendly Farming Network. “We have heard very little from the government on how they will be supporting farmers to effectively make this transition and we urge them to look at appropriate ways to deliver a clear food delivery strategy that supports short, sustainable supply chains during the pandemic and beyond,” he said.

Selling directly to consumers remains difficult, even for farmers who have set up their business that way. Charlie Cole, a livestock farmer at Broughgammon farm in Northern Ireland, said: “It’s been an absolute nightmare. Our business is completely dependent on us selling directly to the customer. So now that the government restrictions are in place, the farmers’ markets and street food events have come to a close and we’ve had to shut the cafe in the farm shop, which are all usually reliable sources of income.”

The cancellation of Wimbledon means its strawberry supplier in Kent is faced with 33 tonnes of perishable soft fruit with no market. Marion Regan, whose great-grandfather established Hugh Lowe Farms in Kent in 1893 with a Covent Garden stall, is now looking at alternatives. “We will find a home for them,” she told the Oxford Farming Conference podcast. She said she was talking to food banks as well as commercial outlets.

The difference between what we eat at home and our tastes when eating out is also causing problems. Our love of mince is a menace to livestock farmers, who have seen the meat market collapse even while supermarkets have been stocking their shelves with meat imported from Poland. People are eating far more mince, which is cheap and comes from the tougher end of the animal, instead of the more expensive cuts, such as steak, that we tend to choose when eating out.

As farmers need to sell whole carcasses, they are forced to sell at far below the true value. “If everyone wants mince, the carcass is massively devalued,” said Batters. “People want to buy British beef. If it has to be mince, OK, but you must balance the carcass [if necessary by mincing prime cuts] and stabilise the price, or people will go out of business.”

Coffee shops used to account for a large proportion of the UK’s fresh milk sales, but when drinking at home people tend not to make the milky cappuccinos and lattes that they would buy when out. Dairy farmers are seeing prices so low that some have been throwing fresh milk down the drain without a buyer to collect it from the farm.

Supermarkets imposed buying limits to stop people stocking up on some items, including milk and eggs. But Batters said there was no reason for limiting the amount of dairy produce people can purchase as there was no shortage of supply.

Small farmers were most at risk from the crisis, Batters warned, as they had less to fall back on and were finding it hard to gain credit extensions from their banks.

Farmers who diversified, as they were urged to, into side businesses such as running B&Bs are also finding those sources drying up. “Normally we would make £7,000 off tourism per year, but that income is going to vanish,” said Polly Davies, a tenant farmer in Glamorgan.

Batters will urge ministers at a virtual meeting on Friday to give British farmers a boost by mandating all food bought by public bodies, including the NHS and the army, to come from British producers.

“The government has a key role to play, that needs to be recognised,” she said. “If there is to be a positive legacy from this crisis, let’s build a more resilient economic future – paying attention to our food and our health, and buying local food, is a key part of that.”