Nicola Sturgeon has announced an immediate £160m boost in pay for nearly 150,000 NHS staff in Scotland, among a package of new spending measures.

The first minister sought to shore up the Scottish National party’s continuing lead in opinion polls by also announcing an increase in support for the poorest students and those from the care system worth more than £20m.

In a bid to beat the UK government’s imminent announcement of a new NHS pay deal in England, Sturgeon said all eligible NHS staff in Scotland earning up to £80,000 a year would get a 3% pay rise in next month’s pay packet.

That increase was being given in advance of a formal deal with NHS unions on a three-year pay deal expected within weeks, she said. It would include nurses, midwives, paramedics and support staff, but exclude doctors and senior executives.

That meant an auxiliary nurse with one year’s experience would be £830 better off after tax, while a healthcare assistant could earn £630 more. Eligible staff earning more than £80,000 would get a flat rise of £1,600, the Scottish government added.

“None of the progress we need to see in our NHS will be possible without the dedication of those who work in it,” she told about 2,000 SNP delegates meeting in Aberdeen.

“We know that for NHS staff and all those who work in our public services, the last few years of pay restraint have been tough. [This] is a £160m investment in those who care for us.”

She added that bursaries and grants for Scotland’s poorest students would increase by £16m next year, while the starting salary for repaying student loans would rise to £25,000 – putting Scottish students on the same starting rate as English students for the first time.

Until now, Scottish graduates had to begin paying off their student loans at a lower figure than in England and Wales. And student support levels had been cut sharply by the last SNP government in 2012, with poorer students forced to increase their loans.

In a further measure, £5m would be spent on giving young people from the care system a new college or university grant of £8,100 a year from this year.

After attacking the UK’s government’s “hostile environment” policy on immigrants and urging a far more progressive migration policy, Sturgeon said her policies were designed to illustrate the benefits of independence. “We are not just talking about creating a more prosperous, fairer country,” she said. “We’re taking action now to build the kind of country we know is possible. And we are using every power at our disposal.”

The mood of the two-day conference was diligent and at times energetic, with the 2,000-seat conference hall regularly at capacity during the sessions on internal party reforms that dominated the agenda.

A number of SNP stalwarts were absent, including recently ousted MPs Angus Robertson and Alex Salmond, the former first minister, while only a handful of the party’s 35 MPs were present.

The most recent YouGov opinion poll, published on the eve of conference by the Times, produced the shock finding that Sturgeon’s personal popularity had fallen into the negative for the first time. She was given a minus two rating, against a plus 15 rating for her nearest rival Ruth Davidson, the Scottish Tory leader.

In contrast, the SNP’s popularity in government grew, with its Westminster support up four points to 40% and up three points to 41% for a Holyrood election.

Sturgeon gave no further indication of her plans or strategy on independence but she defended a recent and highly controversial SNP report on the country’s economy post-independence, called the growth commission.

She said it would increase a growing sense of confidence that Scotland could prosper outside the UK. “I am more certain than ever before that persuading a majority of our fellow citizens that Scotland should be an independent country is well within our grasp,” she told delegates.