When Mark Coburn cycled into St Enoch Square in the centre of Glasgow on a recent Sunday afternoon, there were cheers, balloons and the promise of a shower and a pint. The 40-year-old postman was completing a 1,421-mile bike ride from Rome – across France, and up through England – to home, raising more than £8,000 for local groups campaigning for a yes vote in September's referendum.

A lifelong supporter of independence, Coburn said he had wanted to do something "truly unique" for the yes cause, the idea coming to him while visiting his Italian-born wife's relatives in Italy. Fundamental to his plan was that the money raised would go directly to local groups nominated by the donors, rather than the official Yes Scotland campaign. "I'm raising money for grassroots groups because they are pivotal," Coburn said. "It's coming from the ground up. If we are to win this referendum it'll be down to the grassroots activists. Without them there will be no yes vote."

If his dedication is impressive, his interest in the vote to come is hardly unique, as the nation comes together in debate, although not of course in agreement on which way to vote. About 50 miles north of Glasgow, about 70 locals had gathered on the May Day weekend at Strathearn Community Campus for the launch of Better Together Crieff. This market town in Perth and Kinross is a tourist spot with a perfect ratio of B&Bs, craft emporiums and shops selling outdoor goods. It is also as blue as the surrounding hills in the evening gloaming – the sort of place where one's footfalls echo on the pavement after 6pm.

Musicians at the Scottish independence referendum debate at Victoria Halls, Helensburgh, Dunbartonshire. Photograph: Martin Hunter

These were the sort of people who would normally find it mortifying to talk about politics in public, yet they had been brought there that night by the seriousness of the matter at hand. There was grave if muted agreement when the local Conservative MSP, Liz Smith, informed them: "This is the biggest decision you will ever have to make."

This is Scotland in the early summer of 2014. It is not a foreign country. The people who live here are not automatically more egalitarian or servile, no more optimistic or canny by accident of geography than those living in England, Wales or Northern Ireland. But it is a place full of individuals who are doing things that they have never done before: taking part in campaigning, attending public meetings, having conversations about the future that they want for themselves and their children with an urgency that they have never displayed before.

Until this spring, the consensus at Westminster, and among the London-based media, was that a convincing no vote was a done deal. This is no longer the case – if it were ever so. What is harder to reflect, but necessary for a fuller understanding of what is happening here, now, is how the simple, enormous fact of that vote affects a population.

The Duchess of Cambridge visits Crieff. Photograph: Jeff J Mitchell/Getty Images

There is a much watched clip on YouTube of an STV interview in January with Jim Sillars, SNP (Scottish National party) behemoth and widower of the politician Margo MacDonald. In it he tries to convey the significance of referendum day: "Between 7am and 10pm on the 18th of September, we are totally sovereign. We have power in our hands for the first time in our history. Whether at one minute past 10 we remain sovereign and powerful or whether at one minute past 10 we've given it all away once again and we're powerless, that's the key question."

If the question itself is binary, the anticipation of that sovereignty is uniting. At a women's advice centre in Maryhill, north-west Glasgow – a short walk and a plunge in life chances away from the city's salubrious West End – the women present were those whose trust in politics and politicians has been battered by years of exclusion. None of them intended to vote in the European election, taking place that day. All said they would vote in the referendum "because it's for ever".

What is most striking – and most moving – in the public gatherings has been the quality and seriousness of the listening. At another meeting in Fife, this one organised by the local yes campaign in Benarty, a former mining area in Gordon Brown's constituency, veteran leftwinger Dennis Canavan gave a rousing peroration: "We have an army of footsoldiers … We are going to see the most successful grassroots community-based campaign that Scotland has ever known … I say to you, the people of Benarty, let's go for it!"

While there was applause, it was not unrestrained. Bias confirmation is inevitable where the yes badges are in the ascendant, but this was not a crowd looking for rhetorical kicks. Yet it is another example of people doing things they have never done before. Benarty is the kind of Labour heartland that remains key to pro-independence campaigners: voters for whom yes is not an inevitability, but a journey. The audience there was largely 40-plus, those for whom the devastation of the Thatcher era and the disappointments of the Blair years constitute lived experience.

The Scottish Cabinet hold a Q&A session in Rutherglen. Photograph: Jeremy Sutton-Hibbert/Getty Images

Sheila Connolly was making assiduous notes on the back of a leaflet with an "I love London" pen. She had finally made up her mind to vote yes before coming there tonight, she told me after the meeting. "My father was a great union man. All my family have always voted Labour, but I think that the party has changed." She was not hugely fond of the SNP, she added, although it had done some good things for Scots, "more than anybody else".

This listening is absolutely not uncritical. What is obvious, too, is the knowledge of these audiences. The following weekend, at a Radical Independence Campaign conference in Inverness, a young woman with snowboarding stickers on her notebook started talking to me about the intricacies of land reform. "People are becoming their own experts," she said. "If you'd asked me about land reform a year ago I wouldn't have had anything to say."

Many on the yes side would argue this self-informing comes out of necessity. They express deep frustration at the way the campaign is being presented in the mainstream media. In a recent pamphlet for the Saltire Society, the broadcaster and independence supporter Iain Macwhirter argued that Scotland is observing itself in a distorted mirror, "in which civil society is bent out of shape by the preoccupations of a media that is not its own".

"What has happened," he wrote, "is that the Scottish media, now dominated by London-based papers, has developed a kind of unionist group think: a propensity to accord authority to unionist voices, which has unconsciously unbalanced the campaign."

Men hold up a sign at an anti-independence protest. Photograph: Jeremy Sutton-Hibbert/Getty Images

At the Crieff meeting, Tim Carmichael expressed open frustration at what he saw as the genteel demeanour of Better Together. He cited as an unlikely model George Galloway, who is touring Scotland with his alternative anti-independence campaign Just Say Naw: "We need someone like that. We're hearing very positive things about devolution here so why is that message not getting out?"

Carmichael was born in England, he told me, but is married to a Scot: "People need a Scot telling them what [the unionist] position is about. We need more passion in this." That passion is due to be supplied by Jim Murphy, the former Scottish secretary, who launches his modestly titled "100 towns in 100 days" tour of the country for the Better Together campaign on Monday.

Elsewhere, there is a quiet confidence: that this is a long game, the official campaigning period has only just begun, that supporters of the no vote will remain tight-lipped for now but will turn out on the day in droves, as in the 1980s when a category of voters was identified who would not admit to voting Conservative. But there is anxiety too, in particular that the campaign is becoming divisive, that declaring one's unionist sympathies is deemed anti-Scottish.

Take Margaret Whitham, volunteering at a Blether Together telephone canvassing event in Helensburgh last week. "I can't say I like calling up people cold," she said, "but I feel very strongly about it. The yes campaign are everywhere and if we don't get out there then people will think they won't bother voting because we've lost already. In any situation in life, the people who want to break away make the most noise."

Pro-independence supporters gather in Edinburgh. Photograph: Andy Buchanan/AFP/Getty Images

And that noise is only getting louder. The civic energy unleashed by the yes movement – and it is a movement: cross-party, cross-generation, cross-class – is palpable. Certainly the SNP party machinery is heavily involved, certainly the official Yes Scotland campaign is funded largely by SNP supporters, but not even the weariest cynic could suggest that this is a purely SNP affair.

It is progressive, and within that is a continuing and sometimes fractious debate about the future of the left in Scotland. It is National Collective, crowdsourcing more than £30,000 in under six weeks to stage the summer arts "Yestival". It is the Radical Independence Campaign, organising mass canvasses of some of Scotland's most deprived housing schemes. It is Women for Independence, holding platform-free coffee mornings across the country for undecided female voters, and it is happening in spite of, not because of, the official constitutional campaigns.

The Rev Doug Gay, a prominent yes supporter who made the case for independence at the Church of Scotland's General Assembly, sounded a note of caution: "There's something about being part of an exciting and dynamic campaign that means you can convince yourself that you're winning. But there's a whole swath of people who are not touched by that. There's a quiet, undecided Scotland that needs a different set of appeals to make a difference to them."

This is the 33% identified by the latest Scottish Social Attitudes survey as deeply conflicted; the exclusion of their preferred option of devo max (full fiscal autonomy) from the ballot paper has left them with a difficult choice between two extremes. It's an almost painful position to be in, especially as a first-time voter upon whom, certainly among the young people I've talked to, the responsibility of the extended franchise weighs heavily.

Scarlett Randle, a 17-year-old from Aberdeen, told me: "That's what worries me: we won't know what happens until we get independence, but what if what we want to happen doesn't and we've made a bad choice? I just want someone to take away all the lies and all the stuff and tell me what's best for the country."