The addition of 2,500 extra services daily means that about 85% of the rail network will be running again, back to levels before the start of the last lockdown in December.
Campaigners have urged ministers to do more to underline the safety of public transport, with social distancing likely to be impossible on many trains despite the additional capacity.
Rail companies are asking passengers to travel at quieter times and will be providing information about busy services through personalised alerts to phones.
Passengers on GWR and LNER intercity routes will be asked to check before they travel with some services still out of action due to the cracks found on Hitachi Class 800 trains, although a safety and repair plan drawn up on Thursday has allowed more to run.
Robert Nisbet, a director at the Rail Delivery Group, an industry body, said: “As many people prepare to make their first journey since the pandemic began, we’re ensuring that they can travel with confidence by increasing space and maintaining enhanced cleaning.
“As part of our safer travel pledge, we’ve made journeys more comfortable and reliable for people when they return and while we are adding thousands more daily services to increase space, social distancing may not always be possible.”
Research by the passenger watchdog Transport Focus found 90% of passengers felt safe making train journeys in the past week.
Train passengers numbers are at just under 40% of pre-Covid levels, while bus usage is at about 60%.
Capacity on buses nationwide will be almost doubled from Monday with social distancing no longer required and adjacent forward-facing seats again usable. The bus industry group the Confederation of Passenger Transport said that on busy routes passengers may now need to sit next to each other.
Transport for London, which is running a full network of about 8,000 busesevery day, said most seats could be used from Monday, increasing the capacity of double-deckers to about 60.
Anthony Smith, the chief executive of Transport Focus, said the government needed “to be straight with passengers” that social distancing might not be possible. “The next few weeks will be crucial in helping to rebuild passenger confidence step by step.”
Paul Tuohy, the chief executive of the Campaign for Better Transport, warned that without more help public transport could struggle and congestion increase, adding: “We hope the government continues to send a clear message that travelling by public transport is both safe and desirable.”