Climate change, instability in the Middle East and Brexit will be on the agenda when Boris Johnson meets other world leaders in New York next week.
The prime minister will hold talks with Donald Trump, Emmanuel Macron and Angela Merkel among others at the UN's annual General Assembly.
He will also meet India's Narendra Modi and Irish Prime Minister Leo Varadkar.
The Irish government has said "quite a wide gap" remains between it and the UK over a mutually acceptable Brexit deal.
Speaking on Friday, its foreign minister Simon Coveney said the "mood music" had improved but claims the two sides were inching towards an agreement were "spin".
The UK is due to leave the EU on 31 October unless the bloc agrees to further extend the process. Mr Johnson has said he will not ask for another delay.
Although Brexit is not officially on the agenda of the 74th session of the UN General Assembly, a senior government official said they were "sure it will come up".
Mr Johnson, who will arrive in New York on Sunday, will meet the German and French leaders as well as European Council president Donald Tusk.
It is thought they will discuss a series of ideas put forward by the UK on Thursday aimed at breaking the current deadlock.
"What this gives the PM an opportunity to do is to talk to them at leader level about what some of our proposals are," the government official added.
"At the same time we are under no illusions that there's an awful lot of work to do."
The General Assembly is the largest gathering of world leaders in a single place - providing a forum to discuss issues of global concern.
Nuclear disarmament, sustainable development and global healthcare are among the main issues are on the agenda, while a separate climate summit will start on Monday.
Last week's attack on oil facilities in Saudi Arabia - which Houthi rebels in Yemen have claimed responsibility for, but which the US blames on Iran - will also be discussed.
As well as meeting Mr Trump for the second time since he became PM in July, Mr Johnson is also due to hold one-to-one meetings with the leaders of Turkey, Egypt, Ukraine and Jordan.
The PM, who is expected to be accompanied on the trip by his partner Carrie Symonds, said he had three priorities for the upcoming meeting.
"First, how Britain can work with our European and American allies on peace and stability in the Middle East," he said.
"Second, how science and new technologies can help the world deal with climate change and the threats to biodiversity.
"And third, how post-Brexit Britain will be a better place to invest in and live in."