More than three-quarters of senior NHS staff fear the health service is not ready for the major reorganisation that comes into force in less than two weeks. That is a key finding of a survey of NHS professionals, in both clinical and management roles, who belong to the Guardian's healthcare network. The survey shows that many of those most directly affected by the government's radical reorganisation of the NHS do not think that the new bodies that come into force next month, including the NHS Commissioning Board and GP-led clinical commissioning groups, are prepared for the mammoth task of running the health service.

The 1,100 members of the network who responded to the survey, which was conducted in February and March. Asked "How ready do you believe the NHS as a whole is to take on its new role from 1 April?", an emphatic 76% said "Not ready"; 16% said "Don't know"; and only 8% said "Ready". Respondents also doubt that any parts of the new system will be geared up for the transfer of responsibilities. Two-thirds of respondents felt the clinical commissioning groups (CCGs) weren't prepared. This is despite former health secretary Andrew Lansley putting them in the "driving seat" of the NHS reforms.

More than half of respondents also thought the NHS Commissioning Board, which is tasked with taking over the running of the NHS from politicians was ill-prepared to take the reigns of power. And a similar number felt that local authority health and wellbeing boards, which from 1 April will take control of public health spending in their areas, weren't equipped.

"So close to the deadline and it's incredible the number of organisations/staff that are really unprepared," said one respondent. "I cannot think of a single sector of the NHS that is ready for change. God help the NHS and its patients," said another.

Uncertainty about where the buck stops and who will be doing what under the new regime were recurring themes. "I find it all very confusing, where does accountability lie and what is the nature of the relationship between all these bodies?"; "Working in a large London teaching trust, there are serious concerns about who we are to invoice and who will pay what, and no clarity has been provided."; and "I am in an organisation that is merged into Public Health England [the body set up to improve public health and reduce inequalities nationally]. We know nothing about what is going to happen or even what job we might have or where it will be."

Words like "rushed", "ill-thought-out" and "poorly planned" were used to describe the overhaul. One respondent said: "Too much change is being implemented too quickly at a time of diminished resources and increasing demand"; another predicted that the changes were "going to be a disaster". Doubts were also raised about whether health organisations had the right staff in place to fulfil their new roles. Fifty-three per cent of respondents thought CCGs didn't have the staff they needed and 44% said the commissioning board employees weren't up to the job.

"Not sure the current culture, capacity and capability, or executive and middle-management leadership is of the calibre required to drive the transformational change required," one said. Another pointed out: "All areas are still in the process of recruiting the very same people that have been made redundant [from bodies such as primary care trusts] at the expense of the taxpayer." "I work in a CCG and GP leadership have no idea what they are taking on re[garding] being a statutory body, what that means, how they should behave," said another.

In addition, staff also voiced serious concerns about the delivery of healthcare in their organisation. More than 40% said they had serious concerns, ranging from waiting lists to staff shortages, which they felt compromised patient safety. Moreover, of those who reported these concerns, almost two-thirds said they felt they weren't dealt with satisfactorily. Respondents described a climate of fear and intimidation from management. Some said they had been silenced; others that they were ignored. "The executive team did their best to ignore me and to silence me whatever way they could," said one. "Unsafe staffing levels are routine in my hospital – it has ceased to generate interest," said another.

For those who had not reported their concerns, when asked to explain why they chose not to, responses included: "We are not encouraged to report difficulties", "Fear of retribution by management" and "Healthcare culture is defensive rather than one of learning."

These findings come after the Francis report into the Mid Staffordshire scandal blamed the culture of the NHS for the poor care that led to the deaths of hundreds of patients. The report called for openness, transparency and candour throughout the health system, which means "enabling concerns and complaints to be raised freely and fearlessly, and questions to be answered fully and truthfully", it said.

Mike Farrar, chief executive of the NHS Confederation, which represents most NHS organisations in England, says the survey findings show that more needs to be done to make sure staff are fully confident to speak out when they see practices they are uncomfortable with or that they believe put patients at risk.

"They need to be able to do so knowing they have the support of managers. In turn, employers need to show they are addressing the concerns of individuals who speak up against poor practice. If we don't resolve this issue, there is a real danger we will lose the confidence of staff. And a further risk that we will damage public confidence in our ability to do the job well, and put patient safety at the heart of everything we do."

The Department of Health insists that reforms to the health system "are on track for the start of April". A DH spokesman says: "We know that with any large-scale reform there will be teething problems." But, he adds, the department is in daily contact with health organisations to make sure any problems are resolved swiftly.

A spokeswoman for the NHS Commissioning Board says: "While we are confident the new organisations will be ready to discharge their functions, there is lots to do before they achieve their full potential. We all need to keep learning and listening so we build an NHS that is more responsive, more transparent and more compassionate on behalf of patients."