Boris Johnson will on Tuesday tell the public not to be afraid of using Accident & Emergency facilities and say it is "vital" for people to get treatment.
People should feel "confident" about going in to receive emergency medical care when they need it, the Prime Minister is expected to say.
Last week, it emerged about three in 10 adults would not feel comfortable attending A&E for urgent care if they needed it. A survey of 1,235 people by the Office for National Statistics (ONS) showed that one fifth would feel uncomfortable attending, while eight per cent said they would feel "very uncomfortable".
Mr Johnson said on Monday: "It's vital that those who need emergency treatment this winter access it, and for those who remain concerned about visiting hospitals, let me assure you that the NHS has measures in place to keep people safe.
"Thanks to the hard work and tireless efforts of NHS staff throughout the pandemic, our A&Es have remained open for the public."
On Tuesday, the Prime Minister will visit a hospital to announce the allocation of NHS funding. In total, 117 trusts will receive £300 million between them to upgrade their facilities by the winter ahead of a possible second wave of coronavirus (see video below).
April was the quietest month ever for A&E departments across England, according to NHS England data. Experts have warned of the damaging effects of people avoiding getting medical treatment during the pandemic.
Mr Johnson is expected to reassure those who remain worried about risks that hospitals have taken steps to prevent people from catching coronavirus, including strict social distancing and hygiene measures.
The £300 million has been set aside to enable hospitals to maintain essential services and reduce the risk of Covid-19 infection during the coming months. It comes from a £1.5 billion capital building allocation for the health service set out by Mr Johnson in June.
The hospitals will be able to use the funding to increase their A&E capacity, with more treatment cubicles and expanded waiting areas to ease overcrowding and improve infection control, Downing Street said on Monday.
The funding has been allocated to NHS trusts across the country, with University Hospital Southampton NHS Foundation Trust, Lancashire Teaching Hospitals NHS Foundation Trust and University Hospitals Birmingham NHS Foundation Trust among those receiving the largest amounts.
The upgrades would all be completed by the start of 2021 in time for the peak winter months, the Government said.
Hospitals will be able to increase the provision of same-day emergency care and improve patient flows to help them to better respond to winter pressures and the risks of fresh coronavirus outbreaks, the Government said.
Mr Johnson will say: "We continue to deliver on our promise to build back better and faster, with £300 million allocated today for NHS trusts to upgrade their facilities and improve A&E capacity. These upgrades will help our fantastic NHS prepare for the winter months, helping them to deliver essential services and reduce the risk of coronavirus infections."
Last month, he confirmed £3 billion in extra funding for the NHS in England to get it "battle ready" for the winter. Some of this money will be used to keep the Nightingale hospitals open until March 2021, and for private hospital capacity to continue to be used.
It will also expand the flu vaccination programme this winter and allow hospitals to boost capacity in the health service while also allowing routine treatments and procedures to continue.