Big companies from Jaguar Land Rover and Airbus to GlaxoSmithKline have dominated the headlines with their warnings and preparations for Brexit, but the possibility of the UK crashing out of the EU without a deal on 29 March worries smaller firms just as much, if not more.

Britain has 5.7m small and medium-sized enterprises, defined as businesses with fewer than 250 employees, and concerns about a potentially disorderly departure from the EU span many sectors.

Theresa May’s deal is due to be put to a parliamentary vote on Tuesday. If the government is defeated, MPs will vote on successive days on whether to block a no-deal Brexit and whether to extend the departure date. Meanwhile, British SMEs try to plan for an uncertain future.

Industrial

Alex Ingham, the founder and managing director of the Teesside-based MI Supplies, worries about how the workwear firm will be able to stay competitive if a no-deal Brexit leads to new tariffs and lengthy delays at the border.

The firm imports its biggest four brands, such as Carhartt, from warehouses in Europe. It then adds corporate logos and ships the clothing and equipment to UK customers including fire brigades and construction and engineering firms, within a day.

MI Supplies has been stockpiling products, but not much as it would like after losing its biggest customer, a UK-based firm. The client cancelled a three-year contract worth £2.4m, citing increased cost pressures associated with Brexit. “We are between the devil and the deep blue sea,” says Ingham.

MI’s costs have also gone up by around £750,000 since the EU referendum in June 2016, largely the result of the weak pound. Ingham describes it as a huge increase for a business with an annual turnover of £3m.

The firm has been forced to lay off two of its 14 employees and reduce hours for its remaining staff. “We’ve got so many facets to worry about, it’s hard to know where to start,” says Ingham.

Automotive and utilities

“The bigger concern for us is the free movement of labour,” says Sophie Boothroyd, the finance director of the Shropshire-based Corbetts the Galvanizers.

About 90 of the 120 people working at its Halesfield site in Telford are from eastern Europe. So far only one person has left this year because of Brexit, but there could be more departures, she says.

“There haven’t been any murmurings yet of mass movement back to their native homeland, but it is certainly something we are keeping an eye on.”

The firm has raised pay rates and is considering subsidising staff travel to its factory. It also plans to recruit more people locally and take on more apprentices next year.

The 200-year-old company, which was taken over by a Canadian private equity firm two years ago, specialises in hot-dip galvanising – the coating of steel with a layer of zinc to protect it from rusting. The firm mainly supplies services to utilities companies for buildings and oil rigs and to the transport sector for road vehicle chassis. It has an annual turnover of £12m and made profits of £500,000 last year.

Pharmaceuticals and medical devices

Brexit forced the Manchester-based Elucigene Diagnostics to register its products in Malta this week, including moving a staff member there.

This will enable the company, which makes prenatal diagnostic kits for conditions including Down’s syndrome and testing kits for cystic fibrosis, to continue selling its products in the EU once the UK leaves. The NHS is also a major customer.

“We’ve been trying to wait and wait and wait, but we had no other choice but to trigger our plans,” says Mark Street-Docherty, the chief executive.

The additional cost of about £10,000 is manageable for a business with an annual turnover of £4m, but “it’s another level of complexity of bringing products into the European market”.

Street-Docherty says: “A lot of other firms are not prepared for a no-deal scenario, people genuinely didn’t expect it. The team in the office are in dismay at the fact we are now a month away from our departure from the EU and the terms under which we will leave are unknown.”

Britain’s life sciences sector – pharmaceutical, medical technology and biotech firms and clinical research and regulatory organisations – employs 140,000 people and supports 500,000 jobs in total, including the supply chain.

Aerospace

Jason Aldridge, the managing director at Arrowsmith Engineering, is trying to remain pragmatic about the challenges facing the aerospace sector. “Whatever happens, we’ve got to make the best of it,” he says. “If it was a perfect world I’d prefer a deal that just works for people and business.”

Arrowsmith supplies some of the 22,000 parts in the Rolls-Royce engines for planes such as Airbus’s A380. It’s 70 employees in Coventry produce nickel and titanium alloy components that can withstand temperatures of up to 1,200°C. The company, with annual turnover of £6.7m, has already been working flat out to take advantage of strong global demand in the aerospace industry, and to quadruple exports to growth markets.

Arrowsmith started work in December with its own suppliers to guarantee access to the parts and materials its needs even in a no-deal Brexit, from raw alloys to chemicals and drill bits. It has its own stockpile of chemicals and other suppliers have assured the business that they have got enough stock.

“We’ve looked at the next six months ahead and made sure that material is ordered, here or guaranteed,” says Aldridge.

If tariffs are imposed, Arrowsmith will have to bear the cost for its EU clients, he says. Another concern is the future for its workers from EU27 countries.

The aerospace and defence sectors employ more than 260,000 people in the UK, according to the lobby group ADS.

Construction

Brexit should be used to rebuild British manufacturing, according to John Wood, the director of Canatronics, a small business that supplies lighting and timers for industrial buildings.

“I just wish the government would stop messing around,” says Wood, who voted to leave the EU in the June 2016 referendum. The business is based in the Lancashire town of Chorley, but one of its key suppliers is in Germany.

Wood says the strength of his company’s commercial relationships will help protect supply links, though the company is ready to use an alternative supplier from China if there are delays. The relatively small parts could be flown over at short notice if needed in the case of a no-deal Brexit.

Any significant export delays could be more damaging. The company, which employs five people, could cope with three weeks, but six weeks would be “a bit of a nuisance”, Wood says.

He says he has discussed the possibility of delays with clients in the Netherlands but has not been able to make any firm plans. An extension of the article 50 deadline would just prolong that uncertainty, while a no-deal Brexit would be a mess, he says. “You don’t know what’s going to happen so we can’t put anything in place.”

Employment in the construction industry has gone up steadily since 2014 and the sector employed 1.32 million people in 2017, according to official figures.