Britain's longest-serving monarch, Queen Elizabeth II, turned 93 on Sunday.
Donald Trump will arrive from the Nato summit in Brussels on Thursday.
Roads in front of Buckingham Palace will be shut from Wednesday during the traditional Changing of the Guard ceremony, following the truck attack in Berlin that killed 12 people, British police said.
A beaming Queen Elizabeth II greeted flag-waving crowds outside St Paul's Cathedral on Friday despite being delayed by London's traffic as she made her way to celebrate her official 90th birthday.
Crowds of supporters gathered near Windsor Castle to wish Queen Elizabeth II an early happy birthday, as she marked turning 90 with the release of a photograph of four generations of Britain's royals.
A Pakistani court is set on Thursday to hear a petition asking Britain's Queen Elizabeth II to return the Koh-i-Noor diamond more than 150 years after it was taken from Lahore by colonial forces.