Jack Monroe's Glastonbury diary: I can't believe I sang with Billy Bragg

I was having a pint with Billy Bragg after a busking session in February when he asked me if I wanted to come to Glastonbury. "I run a stage there, the Left Field. You could do a talk, we could sing together, if you like," he said. I remember opening and closing my mouth like a codfish, and then bouncing up and down shouting: "Oh my God, yes, I'd love to. Bloody Glasto! Bloody singing with Billy bloody Bragg at bloody Glasto? Yes!"

And so, a few months later, my girlfriend Allegra and I found ourselves sitting at the kitchen table, compiling a list of "Glastonbury essentials", including S-hooks, Deep Heat and Dioralyte. I had been camping a lot, and fancied myself as a bit of an expert. (As it turned out, the 127 items we listed didn't include a spatula or a scourer, which made frying sausages slightly more of a challenge than it could have been.)

On Thursday morning, we loaded up the car, and began the three-hour trip, including an exciting drive past Stonehenge. On arrival, we were surprised to find Andy and his Land Rover waiting to collect us from the car park. Another volunteer, Callum, found us a pitch not too far from the loos (standard and compostable) and helped us assemble our tent. We blew up beds and pegged in groundsheets, and I started to write my speech for the next day. "I want to go back to the other house," grumbled Small Child. "The one with the guinea pig in …"

Later in the evening, we decided to head out for an adventure beyond the Left Field site. We hoisted Small Child on our shoulders, and ground to a halt a few feet away. Hordes of people as far as the eye could see, crashing and stumbling into one another in varying states of intoxication. We shuffled through them, inching around the swarm of humans ranging from the oblivious to the aggressive, before turning around to retreat to our patch of khaki canvas.

Friday morning was sausages and bacon stuffed into a croissant, with fresh coffee bubbling away in the Bialetti stovetop espresso maker under the canopy. Well, you don't take a chef to a festival for nothing! The espresso maker seemed to be a source of amusement to people walking past our tent, whistling and bubbling away on top of the blue camping stove. I shrugged. I was lying on a blowup mattress in a tent that didn't meet the groundsheet and was pooling water, in a chunky jumper, having managed about four hours' unbroken sleep. I was making no apology for having a cup of decent coffee to get me through the morning.

Come midday, I was standing backstage listening to Michael Eavis giving a moving tribute to the late and great Tony Benn. I had thrown up twice, and was clutching journalist Ros Wynne Jones's arm with fear. I had given this speech a hundred times before, and knew that anyone who came to Left Field would make a receptive audience, but I was terrified. "I can't believe you're singing after this," Ros whispered. "You must be nuts." I shot her a look intended to kill her on the spot, and hissed that I was concentrating on one thing at a time. It was her fault I was here at all – we had worked together on a petition for a food-bank debate in parliament, and she had taken me there a year ago to speak about hunger in Britain. We took our seats on stage.

"I was asked here today to talk about the politics of food banks," I said. "There should be no politics in food banks. But when the government is threatening to close down one of the largest organisations that distribute emergency food aid in Britain, the Trussell Trust, then we know that food banks are a political issue. When senior Tories come out to condemn food banks and their users as reckless, irresponsible, freeloading opportunists, we know food banks are a political issue …"

And so on, until John Harris, who was compering, summed up with: "In the Jack Monroe vernacular, vote the fucking Tories out and join a fucking union." Exactly. Why write a 10-minute speech when a mere 10 words will do?

Before long, I would be on the phone to my dad, boasting that I had just stepped off stage from singing with Billy Bragg at Glastonbury. I could hear him grinning down the line. The truth was, I massively mucked it up. Having shuffled on to the stage to join Billy to sing A New England, I missed my cue twice. He looked at me, I opened my mouth, and nothing came out. "Erm … I'm really sorry, but I'm actually quite shy and I'm shitting myself up here," I mumbled, blushing at the audience and shuffling my feet. Billy laughed and told me I'd feel better if I said, "HELLO GLASTONBURY!" I grinned and shyly squeaked in a very small voice: "Um, so, hello Glastonbury." Billy struck up the introduction for the third time, and I noticed everyone was roaring along with me as I was singing in a broad cockney accent. And I was singing. On stage. At Glastonbury. And I didn't throw up on my boots.

That evening found us standing in a muddy field with thousands of people, arms around each other in a row, swaying and belting out the words to Elbow's One Day Like This as the sun set over Worthy Farm, and surreptitiously shooting Glastonbury sunset photos with one hand, while swigging pre-mixed whisky and coke from a warm can with the other. "Throw those curtains wide, one day like this a year would see me right …"

"Morning boys!" I wandered over to the Fire Brigades Union tent opposite ours, swinging half a bladder of white wine on Saturday morning. "We're up and off, so can I tempt you with my leftover warm chardonnay?" They eyed it suspiciously, and I realised it bore more than a passing resemblance to an extremely large and full catheter bag.

And then, with my second bacon-and-croissant breakfast in a row, the dismantling began. Beds deflated (which was as much work as inflating them), sleeping bags stuffed back into sacks, muddy clothes rammed into a carrier bag, bedrooms unclipped, bags packed, soggy groundsheets rolled up, 17 tent pegs duly yanked out of the ground, one tent stuffed back into its quite-small bag, and we were ready to go home. Andy helped us load the back of his Land Rover and drove us back to the car. As we inched out (following Andy's advice of "second gear, low revs"), it started to pour with rain.

To sum up my first Glastonbury experience? Well, I didn't really feel like I went to the Glastonbury festival I had read about in the newspapers and seen on the telly. I popped my head into it for a look at Elbow and an accidental foray too close to the dance tent, and scurried away again, terrified by all the scantily clad muddy young things and serious festival-goers. I really went to the Left Field festival, a pleasant, safe, family affair, watched over by a contingent of friendly firefighters camping opposite, and spent most of it sitting in my tent with friends and family, or playing Snap with a bunch of kids, or throwing up with nerves in the portable toilets. In the words of my darling, "It was a good adventure, but I'm glad to be home."