The classical singer became engaged to New York-based director Andrew in April when he popped the question during a visit to The Hamptons.
Speaking on ITV's Good Morning Britain today, she said: "I'm very lucky to have met such a lovely man. Did he go down on one knee? He did. I think he went down on both knees – I think he got it wrong!"
Katherine said no wedding date has been set yet but she is turning her attention to planning the big day. One thing she doesn't have to worry about, however, is whether her and Andrew's families will get on.
"They've met, everyone got on. I knew that they would all hit it off, they are very similar people and family is important to both groups so it's great. It's really lovely."
"I'm very, very happy," she added.
Katherine is back in the UK to promote her upcoming album – her whopping tenth!
"It's an album of returning to my roots in all ways, back to the original company, back to the more classical music and the style of my earlier albums.
"It's unbelievable to me [to think this is my tenth album] because I do think back to that first album that I did and I couldn't even believe I was getting the opportunity to do that so to think that ten years later [I'm still doing this]. I feel very lucky."
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