The 'Born Free' singer and fiancé Ben Brewer, who have a 1-year-old son together, got engaged in 2008.
"I've always wanted to get married in a white suit," she told GQ.
"I used to work at a Kodak lab in England, cutting photos after they'd come out of the wash, and in one I saw this couple getting married on a beach in white suits, and their kid was there."
The star also talked about the couple's decision to move from Brooklyn to California.
"I wanted an environment where I could have a lot of friends and family come and stay. That was the important part for me. And in New York I wouldn't have been able to afford someplace where I could have, like, all my friends come and crash out and where I could still have a baby."