'My hands shake. I start too fast, and then speed up. I stop, start again even faster. Un desastre.' Michael Church goes down a storm in Devon

As an amateur pianist, I have had a long and tempestuous relationship with the first movement of Beethoven's "Tempest" Sonata - not the composer's name for it, but a fair description of its lightning shifts in mood. Year after year I've tried to get it under control, and sometimes, after dead- slow practice with the metronome, it has seemed to capitulate. But never for long: the familiar spiral of anxiety, tension, and fudge has always got me in the end. With stubborn perverseness, I've turned a lovely work into a stick with which to beat myself, not to mention those with whom I live.

So there were groans when I set off for Dartington Summer School, armed with the same old piece of music. Would I never give up? Well, not till I'd tried this last resort. Dartington is a hive of studios built round a medieval manor on a hill overlooking Totnes in Devon, and it's a Mecca for amateurs as well as professionals. I wanted to see what a week under the tutelage of top pianists might do.

I was also curious to know whether, after three decades of not singing a note, I still had a usable voice. For the Dartington day starts with everyone - all ages and abilities, opera divas and irredeemable crows - joining choir practice under the baton of a conductor who must whack them into shape for a public concert six days after a standing start. I'd sung a lot of Monteverdi at university, and though Dvorak's Stabat Mater - this year's choice at Dartington - is not in that sublime league, it does have Wagnerian grandeur and might, I felt, produce thrills of a different sort.

Huddled in close proximity to a hundred strangers at nine on the first morning is like starting at a new school. Stand, turn to page five, tenors straight in, please. We basses wait like sheep until our entry - six bars on the same middle register note, then a small jump to C. Nothing much - except that I can't do it. The next hour is excruciating: I don't seem to have a voice at all. Or rather, what there is has sunk an octave. When I last sang, I was a light bass. Now I'm a creaky basso profundo, and the effort hurts. God knows where that voice, once an instrument of pleasure, has gone.

Joanna MacGregor is taking the main piano masterclass. As we wait in the studio, my neighbour casually mentions that this is a bumper year for pianists - of 52 enrollers, 28 are professionals. Uh-huh. A book comes round, in which we put our names and the music we propose to play. It's full of Debussy and Liszt, major concert stuff. "M Church: Beethoven's Tempest Sonata." My palms are suddenly clammy.

A girl plays Scriabin, a boy plays a showy number by Copland, another delivers L'isle joyeuse with flawless brilliance. A burly gent in his forties whirls through Schumann's Kreisleriana. I remind myself that there is a difference between them and me: while I write to eat, they play to eat, so they're bound to be better at it. Unfortunately, this doesn't help. Shall I get that book and cross my name out?

Too late. "Michael Church!" After which, memory is a blur. I look at the keyboard and watch my hands shake violently. I start too fast, and then speed up. I stop, start again even faster. Un desastre. My round of applause - everyone gets applauded when they've done their turn - is amused and sympathetic. The next contender is an old man who plays a slow piece by Rachmaninov for which the Steinway sings beautifully. I've learnt my first lesson.

Watching MacGregor coach other pianists is surprisingly instructive. Time and again she shows problems to be rooted in misguided methods of practice. She has an engaging way of sculpting the air over a player's hands to induce them to bring out the shape of a phrase, and she's hot on role-models. "Listen to Horowitz," she tells a girl whose Liszt is uniformly florid. "He's clear and pure, the effect's held back - but he knows exactly when to go for the kill."

My own lesson begins with a deconstruction of the galloping "Tempest", and moves on to analyse the way I practise. MacGregor's advice seems simple, practical, obvious - some of it so obvious I wouldn't have thought of it in a million years. And on the spot it begins to work: the piece no longer feels external, like a beast to be tamed. Don't expect miracles, she says. But the miracle is that I now know I can play it, given a few weeks' systematic, new-style practice.

One of the beauties of Dartington is that you can wander into classes with anyone you choose. I eavesdrop on Gwendolyn Mok's Ravel masterclass, and watch this New York-Chinese virtuoso demonstrate the affinities between Ravel and Couperin. I observe a student's uptight Schumann unfurl like a flower under the tutelage of a young London maestro called Andrew Zolinsky. Voice, violin, woodwind, organ, flamenco guitar: some teachers are better than others - preoccupation with one's own stardom is a definite disablement - but most operate like doctors, diagnosing ills and prescribing cures.

Their patients are uncategorisably various. The burly gent playing Kreisleriana turns out to be a former airline pilot. The nervy youth magisterially playing Debussy is on leave from the Israeli army. I discover that the Chinese boy who cheerfully murders the same concerto in each piano class is committing similar artistic crimes in cello classes. I notice, with a jolt, that a 15-year-old British prodigy is nonchalantly juggling five balls while waiting to perform: talent is a strange thing. I encounter a surgeon, an anaesthetist, a psychiatrist from Amsterdam; I meet people who have saved all year to be here, and kids who have busked their way across Europe for the privilege of pitching their tent and coming to classes. Many of the overseas players are here on bursaries.

I breakfast with an organist who can no longer play in her native Odessa, where the only organ can't be driven by the city's dwindling electricity supply; she is spending every waking minute at the console in a Totnes church. When, at one of the school's daily concerts, a young cellist from Kazan gives a sensational performance on an instrument fit for firewood, the audience spontaneously digs into its pockets to help buy her a decent one.

Much credit for this extraordinary spirit must go to the school's omnipresent director, Gavin Henderson, who has maintained a unique balance between amateurs and professionals. Just about everybody who is anybody in British music has studied here, taught here, or both: Simon Rattle, who came chaperoned by his parents at 13, is one of a long line of conductors. Throughout its 50-year history, Dartington has periodically been the focus for the musical avant-garde, and with rhythm-freak Louis Andriessen as this year's resident composer - not my cup of tea, but never mind - the radical torch is again burning brightly.

On the final evening we give our choral concert, and another miracle occurs. Our conductor, Graeme Jenkins - one of those globe-trotting Brits who is famous everywhere except in his native land - has somehow turned us into a harmonious unit, and the Dvorak comes over with stunning force. Even I seem somehow to have found a new and usable voice.

"This place has changed my life," says the Latvian bass standing next to me. Mine too, I suspect, as I wander off into the summer night, with a forest of musics still contending sweetly in the air.

n Details of next year's courses from: Jenny Pink, Bookings Administrator, Dartington International Summer School, Dartington Hall, Totnes, Devon TQ9 6DE (tel: 01803 865988; fax: 01803 868108)