'Bairns not bombs" was how the SNP MSP Mark McDonald summed up the independence White Paper in yesterday's Holyrood debate.

Why not bairns now? asked Labour's Iain Gray, insisting that the Nationalists could introduce their free child-care policy tomorrow - well, if they could squeeze an extra £700 million out of the Barnett Formula.

The SNP seem reasonably content with the reception of the White Paper, despite the howls of anger from Unionists about the lack of a plan B on the currency. They believe they have altered the trajectory of the debate by focusing on child-care costs, which they think is of much greater interest to the Scottish voters than abstractions about the currency. Whether it is really an independence issue is another matter.

Nationalist expectations for the White Paper were pretty low, of course, since no-one expected that the unionist parties, the press or the UK Government would be persuaded by their blueprint for a new Scotland. But they console themselves that the media coverage was at least reasonably respectful and the launch went ahead without mishap. Alex Salmond was his usual fluent self, and the SNP feel they have gone some way to addressing their deficit in support from women. Charities and other third-sector bodies were also pretty positive.

They're probably right about bairns being more important to voters than bombs or the Bank of England. But the Yes campaign would have to admit that voters are still troubled by the uncertainties about independence, of which currency is just one. Indeed, it is strange for so much attention to be focused on this one relatively marginal issue. Commentators from countries like Spain, and there have been many in Scotland this week, are mystified by this mono-issue referendum. The contentious issues in independence debates are usually things like citizenship, language, assets, free trade, migration.

The argument about the pound is a lose-lose for the SNP, which is why Better Together are so keen on it. If Alex Salmond did come up with a plan B he would be the target of even greater Unionist excoriation. Imagine if the Scottish Government had said: OK, if the UK won't let us use the pound, we'll set up our own. There would be a chorus of derision and disbelief from Unionist critics. What would it be called: the groat? the poond? the ducat? Who would take it seriously? What would it be worth? What would be the impact on trade if Scotland went the way of Iceland?

The Nationalists would be accused of wanting to erect customs posts at the Border; forcing Scottish families to change their money when visiting their relatives in England; imposing extra costs on Scottish exports to England, and vice versa. UK banks, like Lloyds and RBS, which straddle the Border, would have to spend a fortune on IT systems so that they could conduct transactions in the two currencies. And if the Scottish Government suggested joining the euro, it would be even worse: all these negatives plus the prospect of Scotland becoming another Greece.

So it isn't hard to understand why the Independence White Paper didn't explore a plan B. The Nationalists are right, anyway, in thinking that it is most unlikely that England would want to "deny Scotland the pound" even if it could (sterling is a convertible currency).The logical and sensible thing to do, as former Chancellor Alistair Darling has said, would be for both countries to keep the pound for the time being. This is why neither George Osborne nor David Cameron has ever actually said they favour Scotland being prevented from using the pound.

The more serious issue for Nationalists is the influence the Bank of England might exert over an independent Scotland which remained in a currency union with the rest of the UK. Would interest rates be set with Scottish interests in mind? No, realistically they would not, even if Scotland had full representation on the monetary policy committee of the independent Bank of England, which sets rates.

The SNP argue that this wouldn't matter, at least in the short term, because the Scottish economy is so similar to England's in terms of labour productivity and unemployment rates that a one-size-fits-all would work perfectly well. However, in the 1990s it was not so keen on having an English "straight-jacket" imposed on Scotland. High interest rates set by the Bank were blamed for destroying Scottish jobs because the high pound was hitting manufacturing exports.

But the SNP hope Scottish voters will soon tire of all this currency talk, and start asking Unionists about their alternative vision for Scotland. Having made a pitch on social policy, what are Better Together offering in their pre-Christmas sale? Will they try to match the SNP's child-care proposals?

There has been much talk in the nether-world between the Scottish oppositions parties about a cross-party Unionist alternative to independence, variously called devolution more, devolution max, devolution plus. The Scottish Labour Party's Devolution Commission has certainly discussed a "more powers" approach, though there is no consensus about what it should look like. And the Scottish Liberal Democrats and the Tories do not seem to be overkeen on forging one.

The Scottish Government hopes the focus on child care - which is a policy after all that could be delivered under devolution if the Scottish Parliament had full income tax-raising powers - will smoke out the Unionist devolvers. Will they support a parliament with fiscal autonomy? If the Scottish opposition parties come up with no coherent alternative, the Nationalists will claim the moral high ground as the only party with any true vision of how Scotland could be a better country to live in.

Well, the SNP should perhaps be careful what they wish for. If the Unionists did come up with a firm promise of devolution max then independence would surely lose in next year's referendum. Alex Salmond is betting the house on the calculation that all the talk about more powers from Alistair Darling, David Cameron and the rest is just talk and that, when it comes to next spring, the Unionist cupboard will be bare.

The Nationalists hope the European elections next June will then eclipse the currency issue as it becomes clear to Scots that by remaining in the UK they could be forced to leave the EU after the "other" referendum on British membership. Scots tend to be more favourably disposed to Europe than voters south of the Border, and the rhetoric of separation from Tory eurosceptics and Ukip will show that no constitutional option is without risk.

Indeed, by voting No, Scots would condemn themselves to living in a declining region of a country that is itself moving rapidly away from Europe's mainstream. The real "separatists", Alex Salmond will say, are in Westminster, the old country. Meanwhile, Alex Salmond and Nicola Sturgeon, the odd couple of Scottish politics, will be promising a baby boom to launch Scotland into the new dawn of independence.