The couple is getting married on the 12th October at St George’s Chapel, Windsor, with Sarah gearing up to be mother of the bride.
Sharing her excitement ahead of the couple’s day, Sarah opened up on BBC’s The One Show last week.
Along with discussing the wedding, her charities and future plans, Sarah also let slip a hilarious story about her future son-in-law and ex-husband Prince Andrew.
While chatting on the show, Sarah revealed a private story that took place inside the Royal Lodge in Windsor.
Despite being divorced for 22 years, Andrew and Sarah still live together in the lavish Royal Lodge.
They also live with their dog called Jack, sharing the name of their future son-in-law.
Talking on the show Sarah told the humorous story, saying: “Haha, yes! This is where Andrew is brilliant, you see.
“Cause he goes ‘JACK, GET OFF THAT CHAIR!’ So Jack, our Jack, the son-in-law Jack, jumps up and goes [making a frantic yelling noise] ‘Ahh, what have I done now?!’”
Discussing her relationship with Jack further, Sarah joked about how happy she was with his current job.
Jack is a wine merchant and also works as the UK brand ambassador and European manager for Casimigos Tequila, the brand owned by Rande Gerber and George Clooney.
“The good news is that Jack works as the European manager for Casamigos tequila, so I’m perfect,” said Fergie.
“He’ll just hand me the tequila and say, ‘Come on, mother-in-law, down it’.”
Revealing even more about her daughter’s fiance, Sarah added: “Jack really is a sort of amazing bringer of light and he brings joy.
“I say to Jack, ‘Always just stay yourself,’ and I’d say that to anybody, just be yourself. What else can you do in life?”
Another person who brings the Duchess joy is Prince Andrew, her former husband.
Over two decades since their very public divorce, the two remain very close friends.
Gushing about her former partner, Sarah contained: “The thing about Andrew and I is that we go with our hearts.”
“We go with the family. Unity: We really believe in that. You can see that in the York family, the unity. And it’s all about seeing the light in life. “
Last month, Fergie even stoked the public’s hopes that she and Prince Andrew might reunite romantically.
This was evidenced when the Duchess posted a picture of some beautiful flowers for a special occasion. Her followers then flooded the image with comments, with one fan writing: “When are you and Andrew getting hitched again? You two belong together.”
Sarah Ferguson: Five facts about the Duchess of York
Sarah is the second daughter of Major Ronald Ferguson and Susan Mary Wright.
Her parents divorced in 1974, with her mother going on to marry polo player Héctor Barrantes in 1975 and moving to Argentina. Sarah stayed in the UK with her father, who remarried in 1976 and went on to have three more children.
Sarah married Prince Andrew on 23 July 1986 at Westminster Abbey in London.
She wore an ivory-silk wedding gown designed by Lindka Cierarch which had a 17 foot train and 20 foot veil. As is tradition, Sarah wore a diamond tiara, and her wedding band was crafted from Welsh gold.
The couple spent their honeymoon abroad the real yacht Britannia off the coast of the Azores Islands.
Sarah and Andrew divorced in 1996 after separating in 1992.
However the couple remain on good terms, even living together in the Royal Lodge from 2008 until Sarah moved to a ski chalet in Switzerland they bought together in 2015.
Sarah has written children’s books for many years, her first being a series about Budgie The Helicopter in the early 90s.
She has also been the US spokeswoman for WeightWatchers after famously battling her weight over the years.
On top of commercial endeavours, the Duchess devotes plenty of time to charity, including Children in Crisis, which she founded in 1993.
Fergie, as she is known to friends, uses both Twitter and Instagram.
She has over 200,000 followers across the platforms, and shares many insights in to her life.
Most of the Royal Family are not on social media, but are represented by Kensington Palace, Buckingham Palace, or Clarence House.
Sarah’s daughters, Beatrice and Eugenie, are the exception, with both joining their mother on social media.