Westminster is getting ready for one of the big set-piece events of the parliamentary calendar as George Osborne prepares to deliver his eighth Budget since becoming Chancellor.

Mr Osborne will go to the House knowing that his hopes of succeeding David Cameron in No 10 may be affected by his performance at the despatch box.

Since his Autumn Statement, the economic outlook has deteriorated markedly with uncertainty in China and the eurozone casting a pall over the prospects for the UK's public finances.

As a result, he has to find another £4 billion in "austerity" savings if he is to meet his own self-imposed target of clearing the deficit and balancing the books by the time of the next general election in 2020.

Ahead of his statement, he has trailed some "good news" announcements, including additional support for transport infrastructure projects in the North of England and London and a plan for all schools in England to become academies - although that is strongly opposed by the teaching unions.

However it is the way that he chooses to deal with the difficult issues around deficit reduction that are likely to define the way his Budget is received.

Look out for possible rises in fuel duty and the insurance premium tax as he juggles to get the public finances back on track.

The Scottish National Party urged Mr Osborne to abandon austerity and invest to grow the economy.

SNP deputy leader and economy spokesman Stewart Hosie MP said: "This Budget, like many before, will confirm that George Osborne has failed to tackle the debt, the deficit and the borrowing as he promised, and he will now be forced to admit that he has failed on his trade and exports figures as well.

"This is a Chancellor who remains stubbornly wedded to his failed austerity project - continuing to cut tens of billions more than is necessary to run a balanced budget - despite all the damage that it has done to the economy, our public services and the poorest and most vulnerable in our society.

"Both the IMF and the OECD have said that the Chancellor has scope to invest - we agree and its time he did just that."

Liberal Democrat leader Tim Farron said: "George Osborne made a choice to commit himself to a spending surplus. The results of that choice are now clear - he is missing his own targets but it's the public that will pay for his decision with more years of pain and cuts.

"What George Osborne forgets is that his decisions aren't just some political theatre - every choice, every cut hurts ordinary people.

"Having missed two of his three self-imposed targets, he should do the right thing and abandon his unnecessary surplus target. His surplus isn't needed to balance the books. If he is willing to accept that fact he would be able fund the vital services we need."

The Chancellor and his team depart from 11 Downing Street with red boxes around 1100.

David Cameron answers Prime Minister's Questions from noon, with the Budget to follow at 1230 followed by the Commons debate.

The Office for Budget Responsibility holds a press conference at 1445.

Mr Osborne is expected to use his Budget to deliver a warning about the global economy and insist that he is taking action to prepare the UK.

He is expected to say: "Our economy is strong, but the storm clouds are gathering again.

"Our response to this new challenge is clear.

"A Budget where we act now so we don't pay later.

"In this Budget we choose the long term.

"We choose to put the next generation first."

Shadow chancellor John McDonnell warned the Budget would contain "more stealth taxes and cruel cuts".

He said: "This Budget looks more like a press stunt to hide George Osborne's failures than about any serious policy.

"Take his education announcement, it won't address the real issue in our education system around increasing class sizes, shortage of teachers and lack of school places by just forcing schools to become academies.

"With only one in four schools getting any additional money for the extra hour he's adding to the school day, we will see schools competing with each other for funding and parents will see their aspirations constrained.

"There's further uncertainty of funding when it comes to the infrastructure projects that the Chancellor is set to reannounce. Only one in five projects in his infrastructure pipeline is under construction.

"And when you put all this together with the possible tax cuts that are floated, which will be paid for by more stealth taxes and cruel cuts to the disabled, this Budget from George Osborne looks to not be about the future, but taking us back to the old politics of spin and little substance."

Mr Osborne gets a pre-Budget boost as job figures are announced by the Official for National Statistics.

:: Unemployment was 28,000 lower in the three months to January at 1.68 million, the sixth consecutive quarterly fall.

:: The number of people on the claimant count, including those on jobseeker's allowance, was cut by 18,000 last month to 716,700, the lowest since 1975.

:: Employment has reached a record high of 31.4 million after an increase of 116,000 in the latest quarter. The number of people in work has now risen by almost half a million over the past year.

:: Job vacancies are up by 10,000 to 768,000, the Office for National Statistics reported.

:: Average earnings increased by 2.1% in the year to January, up by 0.2% on the previous month.