Spring in the countryside near Hadrian’s Wall is a scenic season for visitors, all grassy meadows and lambs gambolling in the sunshine. But it’s hard labour for Sally Urwin. The small, cheerful Northumbrian farmer is lambing from 6am to 9pm every day (her husband, Steve, takes the night shift). Her first book, a diary of a year on their 80-hectare (200-acre) farm, has been published, meaning Urwin must also take a bottle-fed lamb to various “scary” literary festivals. Then, looming over every family farm like a particularly black rain cloud, is Brexit.

Farmers have a reputation for looking on the gloomy side of life, but Urwin, 44, is a naturally upbeat person. A Farmer’s Diary combines humour and the stark reality of modern farming, often in the same anecdote, such as the moment the “knacker van”, filled with a pungent pile of dead ewes, drives into their yard just as guests assemble for a wedding party.

In fact, says Urwin, this spring’s lambing – their 150 ewes are expecting 240 lambs – won’t be as bad as last year’s, which happened during the visit from the “beast from the east”. “That was the hardest one I’ve ever done. Steve had lost his other job, I was still trying to do extra work and the weather was just atrocious. I was standing outside, the snow was coming past and it was absolutely freezing. You can’t have lambs out when it’s that cold, so we were running out of spaces in the barn. Somebody sent me a care package because I had moaned so much on Twitter, and that was lovely. Somebody else gave us a lasagne, and Steve burst into tears.”

Urwin, who has two children, Lucy, 12, and Ben, eight, has a lucid perspective on farming, perhaps because she is an “outsider”. Urwin grew up near Newcastle, and was enduring what she calls the world’s most depressing job – marketing manager for a bankruptcy practitioner – when she met Steve, a fourth-generation farmer, on a dating website. She soon joined him at work on the mixed farm – sheep and crops, including wheat and oilseed rape – that Steve had inherited from his father.

Urwin admits she had a “completely” romanticised view of farming. “And other people do. They see you on the farm, and think it’s like a Boden advert. It’s not, and it’s hard work. Things such as having a picnic in the hayfield – it’s never as good as you think it’s going to be. A lot of people say: ‘Can I visit the farm?’ I say: ‘Yes, come and let the kids run,’ but we don’t sit down on tablecloths and have ginger beer.” When she became a farmer, Urwin had another awakening. “I didn’t realise how skint everybody was. Everybody is really skint.”

The land rolls away from the small farm worker’s end-of-terrace house that is the Urwins’ home (the big, old stone farmhouse was sold off generations ago) and they are surrounded by birds, peace and space. Urwin waves towards the fields and the lane of ancient hollies. “We’re not living in some bucolic, amazing place. We’re still trying to keep up with everybody else, but, on the other hand, look at it – absolutely gorgeous. I love it.”

We get a lot of vegans on Twitter saying we’re forcing our sheep to get pregnant, but it’s not like that

Thirty years ago, says Urwin, small farmers could still make a reasonable living, and employed local workers. These days, the paid help is long gone, and the best Urwin can get during lambing is voluntary assistance from her nonfarming 74-year-old father, and her brother, who is a doctor, “so he’s good at injections”.

To survive, the Urwins obeyed the government’s edict to “diversify”. They opened a microbrewery, tea-room and wedding venue in an old shed. But this work removed them from the farming that they both loved. So they sold the brewery and weddings business, although they still receive crucial rental income from it. Sally and Steve then supported their farm with second jobs: Sally does 16 hours a week of marketing work from home, but Steve recently quit his part-time job in an agricultural retailer because overwork made him constantly sick. “I can’t physically drive a tractor – my feet can’t reach the pedals,” laughs Urwin, “and Steve was making himself ill by rushing home, going straight out, working until midnight on the land. My doctor brother says his workload is equivalent. So we’re not complaining. Well, we are a little bit.”

Given the growing number of visitors to the brewery, the Urwins have found themselves farming in a more public way – meeting an urban population living more remotely than ever from the land. Urwin says 99% of visitors are “fabulous”, but she’ll still find a wedding drunk trying to ride their only tractor. Or walkers crossing lamb-filled fields, with their dogs off the lead. “When you say to them: ‘Please don’t do that,’ they say: ‘I’m in control of my dog.’ Yes, but the sheep don’t know that. I come from a townie perspective, so I can understand. I show people around the farm, and a lot of people don’t know the difference between hay and straw. I didn’t when I first met Steve.” A party of visitors once found Urwin asleep – exhausted – on the straw next to the lambing shed door, and asked for the farmer. They were amazed when she said she was. “I refuse to say: ‘Oh, I’m the farmer’s wife.’ It makes me sound like I’m in a nursery rhyme or I stand in the kitchen making yorkshire puddings and pots of tea,” she writes.

The life of a modern livestock farmer increasingly involves defending their business on social media from critical vegans. Urwin explains that many animal welfare arguments don’t apply to small, traditional operations, which are a world away from “factory” farming. “We get a lot of vegans on Twitter saying we’re forcing our sheep to get pregnant, but it’s not like that,” says Urwin. Their tups (the males) – “horrible looking things”, laughs Urwin – are put with the ewes once a year, and the tups are often given short shrift. “The ewes will only ‘stand’ for a tup when they want to,” she says.

Ultimately, however, even if she is raising animals to live good lives outdoors, these lives are cut short to be eaten. Urwin has made a point of visiting the abattoir where her lambs go. “I don’t want them to know that they’re being slaughtered, and they don’t. At least, I can’t see that they do.” The worst moment, according to Urwin, is parting with ewes that have given them six years of loyal service (they are sold, cheaply, for mutton). “You put them on the trailer, and they try to run towards you, rather than away from you. But we wouldn’t have the sheep if we didn’t also sell them for meat. I’ve got to keep thinking of that.”

Urwin would like more local abattoirs, so stressful travel could be reduced for livestock. Ideally people would eat less, higher-quality, meat that they could sell at the farm gate. “But I’m skint, so I can understand why people buy cheap food,” she says. “We’re worried that, with Brexit, we’ll get a flood of imports with low-quality antibiotic-filled meat. But I tend to keep off subjects like that. I get shouted at a lot by people on Twitter, mostly by angry vegans, although some of them are very nice.”

Facebook Twitter Pinterest Sally Urwin … ‘I refuse to say: “Oh, I’m the farmer’s wife.”’ Photograph: Gary Calton/The Observer

Social media causes Urwin anxiety, but there is an upside – she and other farmers are increasingly honest about their mental health problems. Loneliness in farming has been exacerbated by the loss of communal farm labour, she points out, but social media helps farmers support each other. Urwin has just been gathering tips online about how to offer farm visits to the public; she is already part of the FaceTime a Farmer programme, which connects schools with farmers.

Urwin is also broaching another taboo, about farming finances. Despite the Urwins’ assets, their profits are variable, and tiny. Last year, she and Steve sought help from an agricultural charity that helps struggling farmers pay their household bills. “We don’t tell people that because a lot of the older farming generation don’t wash their dirty linen in public,” she says. “I thought: feck it, I’m just going to let people know how bad it is. I’m a bit worried about that because I haven’t told many people how desperate it got last year. It’s better now.”

Then along came Brexit. There’s one certainty amid all the uncertainty over leaving the EU: the money given to British farmers via the common agricultural policy will mostly be put to other uses by future British governments. All farmers receive a “basic payment” subsidy based on their hectares of cultivation. The Department for Environment, Food and Rural Affairs (Defra) has announced it will phase out these payments by 2027. According to another farmer who works closely with Defra, the government privately predicts that one-third of farms will go out of business.

Can the Urwins survive? Sally admits she is worried, and calls Steve over to join our conversation. “The basic payment is our profit,” says Steve. “You take that away, we’re break-even. If we had a bad farming year, we’d be in big losses. The traditional farm will no longer, in my opinion, be viable, without off-farm income. It’s going to be the big estates who …”

“… will suck up all the small ones,” says Sally.

The familiar answer is to diversify, but the Urwins have already done that. They have considered relocating to Scotland, where land prices are cheaper. But they’re still hoping they can save their farm by expanding their camping, and diversifying into free-range chickens.

So what is the appeal of a physically and mentally taxing sub-minimum-wage job with no secure future and additional hassle from the public? “Because it’s a dream to live here,” says Sally. “People have said to me: ‘Why don’t you sell up and live off the proceeds?’ I don’t think we could because we’d miss it so much. There are many more positives than negatives. I am really grateful to be here. It sounds like Disney, but I love seeing the wildlife and I love having that connection with the animals. But it would be nice to earn a decent wage.”

A Farmer’s Diary – A Year at High House Farm by Sally Urwin is published by Profile on 4 April