The 47-year-old singer married wife Dawn - the mother of his children Daniel, 17, Emily, 15, and nine-year-old Daisy - 18 years ago and he is keen to reaffirm their commitment to one another as a gesture of appreciation for how supportive she has always been about his career.
He said: "I want to do that, for both of us and for the kids, because ultimately that's what it's all about.
"She's the one who has allowed me to do what I do. She's the one who does all the parents' evenings, the one who is there with Coco Pops all over the kitchen floor when I get to walk out of the door, she's the one who makes our life what it is. And it's not always easy."
And Gary - who met Dawn in 1995 when she was a backing dancer for his band Take That - credits his wife for bringing him back from the brink when he was left depressed and overweight when his career slumped and he was dropped by his record label in 2000.
He recalled to Event magazine: "I remember waking up one morning and I was enormous. I was a mess and I thought, I am not the man she married. It was Dawn who got me to go to the doctor [for depression and weight issues], and it was because of Dawn that I went.
"But one thing I also know is that even at my worst I never once felt she was going to leave me because I knew - in spite of everything - she was always there for me."
Despite his success, the 'Patience' hitmaker can always rely on his children to keep him grounded.
He said: "I come off stage and I drive home. Nothing brings you back down to earth like coming in the house and realising one of your kids has gone off with your headphones or your computer lead - you're not so special then."