Britain must reconnect with the rest of the world with major resets in climate change policy, and in the country’s relationships with Europe and with the global south, foreign secretary David Lammy has said in an interview with the Guardian before his first international trip.

Lammy has taken up his position, one of the four great offices of state, at a time of immense foreign policy challenges, from two major wars to global inertia about tackling a warming planet.

“The world is a dangerous divided place, and this is a tough, geopolitical moment with huge challenges for Britain, but I’m excited about the project which is reconnecting Britain with the global community,” he said in his vast new office at the heart of the Victorian-era Foreign, Commonwealth and Development Office building in Whitehall.

For years, the UK has been caught up in “an inward-looking conversation”, he said, as the impact of the Brexit referendum and years of troubled efforts to implement it soaked up political energy.

Now, that must end: “Britain has to start reconnecting with the world.” Resetting relations with Europe is a particular priority and his first trip abroad this weekend will take him to Germany, Poland and Sweden, to meet his counterpart in each country. He will then travel on to a Nato summit in Washington, with prime minister Keir Starmer.

“Let us put the Brexit years behind us. We are not going to rejoin the single market and the customs union but there is much that we can do together,” he said. “I want to be absolutely clear, European nations are our friends.”

Areas of cooperation include energy and climate, but most pressingly security. “With a war in Europe we must continue with defence spending and work closely.

The meetings are designed to signal his commitment to working closely with key European partners, before Britain hosts a summit of the European Political Community on 18 July. European allies will be particularly important to Lammy’s plans for supporting Ukraine and tackling climate change if Donald Trump wins a second presidential term in November’s US elections.

For the next five months Lammy will have to court both the Biden administration and the hectic entourage of Republican candidate Donald Trump, who has historically preferred Nigel Farage to even Conservative British politicians.

“We’ve been knocked about, and our economy and our country has been knocked about by world events. I’m conscious of that and I’m going out into the world in this role immediately,” he said. “I’m excited to roll up my sleeves and get stuck in.”

One area he is likely to face immediate pressure for action is on Israel’s war in Gaza. The party’s position cost it several seats, and although the manifesto committed to recognising Palestinian statehood as part of a peace process, it did not include a timeline.

Lammy said he “wanted to go back to a balanced position”, saying he would use all diplomatic efforts to push for a ceasefire. “it is very clear that we want to see a ceasefire and we have been calling for that since the end of last year,” he said. “The fighting has got to stop and the aid has got to get in.”

However, Lammy also wants to look beyond the UK’s neighbours, and the “special relationship” across the Atlantic, to focus on resetting ties with countries across the global south, and adjusting to a multipolar world. If Britain did not offer trade and diplomatic opportunities, it would open the door for other countries including China or India to build alliances and make money.

“I’ve heard too many complaints, prime ministers saying they’ve struggled to get an audience with our own prime minister, countries like Indonesia,” he said, pointing out that Indonesia has one of the largest Muslim populations in the world. “So I think there’s a lot to attend to.”

The struggle to source vaccines during the Covid pandemic highlighted global competition, he added. “They looked to us for help, they didn’t get the help, so they turned to India or China.”

“We’ve got to recognise that it’s a competitive world. Turkey is opening up embassies across Africa, we aren’t the only players. The world is so different.”

His approach will include “listening, not just preaching,” he said, highlighting a call he made just hours after his appointment on Friday. He rang a group of Caribbean leaders, to discuss the devastating impact of Hurricane Beryl.

“They were delighted that I was calling, reaching out to them in a time of immense crisis, one that’s existential for them.”

Lammy admitted spending three years preparing and thinking “every day” about taking up a role he considers the “pinnacle” of his political career.

“I don’t come into this job wanting higher office, this is as high as it gets,” he said. He insisted he was not daunted by the weight of the role he had taken on, even though he was very aware of the challenges ahead.

“You can’t sit in this room and not be very conscious of the history,” he said, describing the moment he walked up the staircase for the first time and was confronted by a bust of Ernest Bevin, the post-second world war Labour foreign secretary who played a key role in the creation of Nato.

He referred the transformation in Britain that means a Black working-class descendant of enslaved people now runs the ministry that a century earlier was the seat of empire.

“I think that Curzon 100 years ago sitting in this office, his main job as viceroy of India would have been to convey a sense of British strength in the world,” he said.

“I am also conscious that Britain has a huge role to play in a very dangerous world of course, but there’s also a story to tell back here at home, about the world, to Britain.”

He plans to stay connected to the roots that inspired his long journey to the top of British politics, while he works to connect Britain to the world, he added.

“I’ve been in politics now 24 years, and I’m thinking about my parents and their sacrifice,” he said. “They’re no longer with us, but I’m going to see my godmother after this in Stepney Green.”