Liz Truss insisted the UK will “ride out the storm” of the worst cost of living crisis in a generation as she launched her premiership with a brutal cabinet clear-out.

In her first address as prime minister in Downing Street, she pledged to be “hands on” in urgently tackling the energy crisis with plans to freeze bills expected within days, as her survival in No 10 depends on them.

Truss is expected to announce plans to freeze energy bills at about £2,500 a year until 2024 in the first major act of her premiership – but is unlikely to claw back the cost through customers’ future bills, leaving the taxpayer to pick it up instead.

Within moments of taking over, Truss was putting the finishing touches to her cabinet which saw close ally Kwasi Kwarteng appointed chancellor, Suella Braverman, who stood against her in the leadership contest, taking over from Priti Patel at the Home Office and James Cleverly promoted to foreign secretary.

Her closest political ally, Thérèse Coffey, takes over from deputy prime minister Dominic Raab after he described Truss’s tax plans as an “electoral suicide note”. She also takes on the role of health secretary. The appointments mean that for the first time in history none of the great offices of state are held by white men.

However, Tory MPs and green campaigners were alarmed by the new business secretary Jacob Rees-Mogg, who has decried “climate alarmism”, being handed direct responsibility for energy and climate change, after she struggled to find a dedicated minister to fill the role. Alok Sharma has been reappointed chair of Cop26, the UN climate change conference.

Truss rejected calls to appoint a unity cabinet to bring the party together after the bruising leadership contest by sacking all the major cabinet-level supporters of her leadership rival Rishi Sunak, including Dominic Raab, Grant Shapps, Steve Barclay and George Eustice, while the former chancellor himself ruled out of taking a role.

Instead she appointed loyalists including Ben Wallace, staying on as defence secretary, Wendy Morton as the Tories’ first woman chief whip, and Brandon Lewis, who infamously admitted the government would be willing to break the law in a “specific and limited” way, as justice secretary.

Penny Mordaunt, who Truss beat to make the final two in the leadership contest, was rewarded with leader of the Commons, while Johnson stalwart Kit Malthouse will become education secretary. Nadine Dorries quit as culture secretary and is expected to go to the Lords, prompting a byelection, with Michelle Donelan taking over her job.

Anne Marie Trevelyan was appointed transport secretary, with the former leadership candidate Kemi Badenoch to trade, Chloe Smith the new work and pensions secretary and Ranil Jayawardena becoming the environment secretary.