LONDON—The United Kingdom and the European Union are expected to seal new deals on fishing rights and defense as officials meet in London on Monday to discuss closer ties in their first official summit since Brexit.

Britain and the European Union have agreed to a landmark deal aimed at “resetting” their post-Brexit relationship, easing restrictions on travel and work for hundreds of millions of people on the continent.

Although the UK prime minister is facing a backlash from his predecessor Johnson and other Eurosceptics over his “landmark” reset deal with the EU, Starmer and his officials insisted they had presided over successful negotiations,