The UK is facing an “absolutely seismic moment”, John Swinney has said, with the prospect of the election of first ministers in Scotland, Wales and Northern Ireland in May who are all committed to the break-up of the union.

Speaking at the Scottish National party’s campaign conference ahead of the Scottish parliament elections, the first minister told delegates: “For people watching around the world, there could be no clearer sign that Westminster’s time is up.”

With the prospect of nationalist parties winning in the Welsh Senedd and the Northern Ireland assembly, as well as at Holyrood, and support for Scottish independence polling consistently about 50%, Swinney said Scotland “can lead this great wave of change”.

Ahead of an SNP campaign during which Swinney has pledged to put independence front and centre, despite that strategy backfiring at the 2024 general election, he said: “We are closer to becoming independent than we have ever been. Support for our cause has never been at such sustained high levels.”

The SNP is currently leading the polls for Holyrood, ahead of Reform UK and Scottish Labour – whose previously buoyant support has collapsed in the face of repeated Westminster missteps. A YouGov survey last month put Scottish Labour on 15%, behind Reform at 20% and the SNP at 34%.

Praising the “sense of community” shown by Glaswegians in the hours and days after the devastating fire that gutted a historic building in the city centre last Sunday, Swinney told the conference: “We will stand by our biggest city in its hour of need.”

He announced a £10m recovery fund to support the council, businesses and agencies and said the Scottish government will also underwrite the £1m cost of clearing the fire-ravaged site, adding that the money “should not come from the public services that Glaswegians rely upon”.

Framing a series of voter offers as “building blocks of an independent country”, Swinney also promised that if re-elected his government would roll out subsidised childcare, based on family income, for every child from nine months old to the end of primary school and available 52 weeks a year.

The SNP leader also said he would create a £100m First Homes Fund to give up to £10,000 in support for a deposit for first-time buyers, to break young people out of the “rent trap” in Scotland and help “a generation let down by Westminster”.

Countering Westminster parties who have criticised his government for speaking out on world events, Swinney told the audience: “We will not stay silent while the world burns,” before calling on the US and Israel to end their war on Iran.

“The Iranian regime have terrorised their own population. Now, those self-same civilians are dying at the hands of American and Israeli bombs. So let me be clear: the unjustifiable actions of the United States and Israel have no basis under international law. They must stop.”