William grew up in Kensington Palace, living there as a child while his parents, Prince Charles and the late Princess Diana, were married, and then staying on with his mother after their divorce.
Princess Diana used the palace as her primary residence until her death in 1997.
"They won't live in the whole place," Larcombe told "GMA." "It's an enormous, sprawling building."
William and Kate will share space with other royals who also live in the palace, which is broken up into a number of apartments.
The late Princess Margaret, the queen's younger sister, lived there for many years, and it was also the birthplace of Queen Victoria.
But it is Princess Margaret's apartment, where she is said to have hosted the Beatles and others when she lived there, that will become William and Kate's new home.
"They will be moving into a small apartment temporarily while, we believe, while Princess Margaret, the Queen's late sister, while her old apartment is completely rewired, renovated, and security upped," said Larcombe.
The couple plans to complete their move before embarking on their first official overseas trip to Canada and the United States later this month.
William and Kate will embarkJune 30 on a nine-day, eight-city tour that will take them from Ottawa and Montreal through the Northwest Territories of Canada before making their way down to Los Angeles for a grand finale.
The overseas trip will mark their first as a married couple, and an opportunity for the newlyweds to showcase the new breed of monarchs that some are calling the "modern royals": going to college, having careers and marrying for love.
It will also be a chance for royal gazers to watch how the young couple will put their own stamp on centuries of royal tradition, and how well Middleton's "dresser" is doing.
Palace watchers expect her wardrobe for the U.S. and Canada tour to include three dress changes per day, amounting to 40 outfits in all for the young bride.
While Diana famously drew from designers and fancy gowns, Middleton, 29, has gone for more affordable and accessible wear, including a Burberry trench coat that sold out as quickly as photographs of her in it surfaced.
Palace officials stress that 'dresser' does not mean 'stylist,' though, and that Middleton will still choose her own clothes.
She will also appoint her own stylist. Middleton will reportedly personally interview the applicants, and hopes to appoint someone before she and William fly to Canada on June 30.
During their visit, which is being paid for by the Canadian government, the newlyweds will tour the Canadian airfield where Middleton's late grandfather, Peter Middleton, was based as an RAF pilot during the Second World War.
They will also make time for more lighthearted moments when they visit the country's smallest province, Prince Edward Island, the location featured in Middleton's favorite childhood book, "Anne of Green Gables," and open the Calgary Stampede, the world's largest rodeo.
Once in the United States, the couple is expected to attend a series of charity events and meetings in the Los Angeles area.
Palace officials say the couple will take scheduled flights back from Los Angeles, not the private jets long favored by royals such as William's father, Charles. And the Canadian government will pay the cost of flying William and Kate to Canada on a jet.
The Associated Press contributed to this story.