Crouching in a gloomy shed in Somerset, I am squinting through a light cider hangover at a new-born, speckled white lamb. My belly is groaning and so are my legs, and thanks to an over-expansive gesture by farmer Brian I have just taken a light spattering of sheep placenta in the face. But I can't remember the last time I felt so relaxed.

I am not some kind of weirdo, but taking a Cart- wheel break on a small sheep farm near Arthurian Castle Cary, testing its theory that countryside weekends are good for farmers, the environment and the mental health of stressed-out Londoners. Cartwheel Farm Tourism is a not-for-profit organisation, run by farmers , that promotes rural breaks, while the cottages and b&bs it represents are family-run and eco-friendly.

Which is how five friends and I find ourselves whizzing gratefully out of London to spend the weekend grinding barley in an ancient mill, hiking across fields in unsuitable footwear and filling our faces with local cheeses before trotting into the lambing shed to perch on bales and gawp at the miracle of birth.

The six who arrive at Castle Cary station are a ragged bunch: a journalist, a probation officer, an IT whizz-kid, a publisher, a medical student and a local government officer. By the time we have negotiated the Friday evening underground to Paddington, we need some serious relaxation.

In our cab from Castle Cary, we start to get the picture. The Somerset lanes are empty of rush-hour traffic, but our driver winds slowly around the corners, careful for badgers straying from their pathways. The lane up to Gant's Mill Farm is lined with nodding daffodils, and in the fields ewes watch warily as their week-old lambs kick up their heels. The mill is quiet, although it can generate a steady 10kw of green electricity, much of which it feeds back into the national grid. Creeping wearily into the cottage we find sunny yellow rooms, with the millstream shushing quietly beneath them. We sleep the sleep of the just.

In the morning there is plenty to do. In one booklet, owners Brian and Alison list the animals found near the farm: 20 badgers, two buzzards, six lazy black cats, foxes, owls, kingfishers, rabbits, 150 sheep. Guests should try the breakfast, which has taken on the status of a local legend. After that, exercise, country-style. A book of walks is illustrated with pictures of the couple and their dog, cresting hills and leaping over stiles.

If you are aprobation officer and you haven't got your wellies, you may skip the walks and choose the stroll into Bruton, past the millstream flowing under the kitchen of Gant's Mill Cottage. The Sun Inn serves Thatcher's cider in an unseasonably sunny beer garden and The Olive Bowl delicatessen will fill you so full of chicken and tarragon pie that you may have to be rolled home. My friend the IT manager swings recklessly over a rope bridge. The publisher waves to the passing London train.

The pride of Bruton, though, is the award-winning Truffles restaurant. It is run by Mark and Deborah Chambers, two London escapees. They use local ingredients, and the cheese comes from nearby Wyke Farm. The Red Devonshire Beef is so good that canny locals phone ahead and order their fillet in advance. You don't want to know where the lamb comes from.

We find out on Sunday afternoon, when Brian discovers us working off the previous night's meal by counting the tadpoles in the garden pond. A ewe is about to lamb and needs some assistance. He offers his sinister orange gloves to the medical student. "I haven't done obstetrics!" she squeals.

The ewe is fed up and snuffling in a corner, and hardly protests when Brian does his thing. In an instant, a new white lamb is wobbling to its feet, bleating perplexedly at this strange audience. The London train rattles by, but we seem to have forgotten that other life of pre-packed vegetables and commutes. Gant's Mill has worked its magic.

THE COMPACT GUIDE

HOW TO GET THERE:

Katy Guest travelled with Cartwheel Farm Tourism (01392 877842; cartwheel holidays.co.uk), the leading non-profit, rural tourism organisation in the South-west. Its aim is to promote quality short countryside breaks in Devon, Somerset, Cornwall and Dorset and support the countryside by helping businesses become more competitive. Gant's Mill & Garden (01749 812393; gantsmill.co.uk) is open for day visits and offers b&b from £35 per person per night or self-catering from £235 per week for a cottage sleeping six.

FURTHER INFORMATION:

Truffles restaurant (01749 812255; trufflesbruton .co.uk), 95, The High Street, Bruton.