When the Queen gave the property to the Duke and Duchess of Sussex ahead of their wedding in 2018, the pair renovated it, but only lived there for a short time before stepping down as senior royals.
Frogmore has been prepared for Harry’s return over the past few days, a source told The Sun.
The insider said: “Eugenie and Jack were handed the keys last year and told they could use it while Harry and Meghan were in America.
“The cottage is now literally split into two, meaning Harry can isolate in one half of the house without ever coming into contact with his cousin and her family.
“It has been set up for his return after last-minute plans seemed to work when he was back for the Duke of Edinburgh’s funeral in April.”
Prince Harry, 36, and his brother Prince William, 38, will unveil a statue for their late mum at Kensington Palace on July 1, which would have been Princess Diana’s 60th birthday.
The two brothers have been working on and designing the statue since 2017.
A plinth has been laid in the palace’s Sunken Garden, said to be Diana’s favourite spot in the grounds.
In 2017, the 20th anniversary of her death, the spot was transformed into a tribute to Diana, with a display of her favourite flowers including white roses and lilies, tulips and daisies.
Sean Harkin, Kensington Palace’s head gardener, said the choice of flowers reflected Diana’s love of cream and white blooms.
The ceremony at the beginning of July will also be the first time Harry meets his relatives after accusing his family of “total neglect” on his recent documentary with Oprah Winfrey, The Me You Can’t See.
He said that he and Meghan – along with son Archie – “spent four years trying to make it work” but their requests for help when Meghan was suicidal were “met with total silence, total neglect”.
He said: “We did everything that we possibly could to stay there and carry on doing the role and doing the job. But Meghan was struggling.
“That feeling of being trapped within the family, there was no option to leave.”
But despite this, a source said: “Harry has said he will do his utmost to be there.
“He wants to put on a united front with William and pay an appropriate tribute to their mother.”