The Government has been accused of acting "like some tin-pot dictatorship" with its plans to send in the Army and police to cover for striking health workers on Monday.
Christina McAnea, the worker union Unison's Head of Health, told ITV News the proposals were "astonishing".
Midwives, nurses, ambulance drivers and other NHS staff in England will walk out for four hours on Monday in a row over pay, while health workers in Northern Ireland will also take action.
A memorial service will be held this evening for murdered British hostage Alan Henning.
His widow, Barbara, and children Adam and Lucy are expected to attend the ceremony at the British Muslim Heritage Centre in Whalley Range, Manchester.
The tribute entitled His Life and Legacy Remembered will include speeches from friends of the popular 47-year-old taxi driver and also faith and political leaders.
Organisers urged the public to "join together to remember an extraordinary individual and the need to continue his legacy of humanitarian aid work".
On their Facebook page, they added: "This event is to remember Alan Henning, the work he did and pay tribute to the legacy he has left behind.
"This is for people of all faiths and none to stand together, unite and continue the work."
An Alan Henning memorial fund for his family, set up by one of the event's organisers - friend and fellow aid worker Dr Shameela Islam-Fulfiqar - on the Go Fund Me platform, has raised more than £25,000.
Another online fund, set up by a community group in Walkden, Salford, has raised nearly £9,000.
Last Sunday, Mrs Henning and her family joined hundreds of well-wishers at a service of "reflection and solidarity" at Eccles Parish Church in Salford.
A video showing the brutal murder of Mr Henning - who was kidnapped last December in Syria by Islamic State (IS) militants - was posted on the internet by the group last week.
Mr Henning, from Eccles, was captured while delivering food and supplies on an aid convoy to refugees.
The UK Independence Party say they're on the way to making a huge impact on the political map of the North West after they ran Labour very close in the Heywood and Middleton by election.
UKIP say they can make big gains in the general election next year.
This video contains flash photography.
Nigel Farage has hailed Ukip's performance in the Heywood and Middleton byelection as "extraordinary" and "beyond my wildest dreams".
Although the party fell 600 votes short of victory, they dramatically reduced Labour's majority, which had been a relatively comfortable 6,000.
Speaking on a walkabout in Clacton, where Douglas Carswell became Ukip's first elected MP, Mr Farage also repeated that in the north "if you vote Conservative, you get Labour" - mocking the Tories' claim that "if you vote Ukip, you get Labour".
Labour's narrow victory in the Heywood and Middleton byelection shows "the scale of disillusionment with Westminster politics", Ed Miliband has said.
Speaking alongside the new MP Liz McInnes, the Labour leader said this disillusionment had led long-time Labour voters to side with Ukip - who came second in the seat, just 600 votes behind Labour.
Labour leader Ed Miliband said the Conservative Party lost a seat "in their own backyard" last night as Douglas Carswell took Clacton for Ukip.
After congratulating Labour's newly-elected Heywood and Middleton MP Liz McInnes, Miliband stressed that the Tories were also "in retreat on what used to be their frontline in the northwest."
He continued, "But there won't be a shred of complacency from us as we reach out to all of those voters who didn't vote Labour and those who didn't vote at all."
The Ukip candidate for Heywood and Middleton has said he would have won the seat if he'd 'had two more days,' and Labour were taking voters in the North 'for granted.'
Liz McInnes won for Labour by the skin of her teeth with 11,633 votes. A lead of just 617 votes. The victory was well down on the 18,499 votes (40.1%) the late Jim Dobbin won with at the 2010 general election.
Ukip's John Bickley came second on 11,016 votes.
Newly elected Labour MP for Heywood and Rochdale, Liz McInnes dismissed the challenge from UKIP. McInnes won the by-election with just 617 votes. There was a turnout of just 36%.
The newly elected Heywood and Middleton MP Liz McInnes said she'd put her efforts into protecting the NHS.