The 69-year-old musician – who has been married twice before – is planning a small intimate ceremony in front of his close family before flying to New York to celebrate with his American fiancee's loved ones.
A source told the Daily Telegraph newspaper: “Paul loves Nancy very much, but does not want a big wedding."
Nancy, 51, previously admitted the couple were planning a civil ceremony to make their union official.
The heiress – who has been in a relationship with the singer for four years – said: "It will be small. Just our families. I don't know the exact date. And don't ask what I'll wear because how dressy do you get to stand before a Justice of the Peace in his chambers, which is exactly what we're going to do."
Former Beatle Paul was first married to Linda McCartney from 1969 until her death from breast cancer in 1998 and then to former model Heather Mills from 2002. Although he didn't officially divorce Heather until 2008, they separated in 2006.
Nancy has been married once before, to Bruce Blakeman.
The 51-year-old businesswoman is said to have been a big hit with the 'Drive My Car' singer's five children, Heather, 48, Mary, 41, Stella, 39, James, 33, and Beatrice, seven.
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