Arron Walshaw, 32, and his fiancee, Ceri Hall, 23, from Ossett, can plan their dream wedding after they scooped the seven-figure Lotto Raffle prize.
Had the other shopper at the Tesco Extra store not let him go first, Mr Walshaw believes he would not have had time to play.
He said: “We had a free Lucky Dip ticket from the previous draw to use and I knew it was only minutes until the draw closed.
“I popped in to a nearby shop where me and another lady approached the same cashier.
“She must have seen that I was in a rush because she insisted I went before her.
“What a stroke of luck that turned out to be! I don’t think I would have been in time to buy my ticket if she hadn’t let me go first.
“We would love to meet her again and say thank you for changing our lives!”
He bought another Lucky Dip and that evening the couple counted their collection of pennies and they were “chuffed” to find they had £50 for a camping trip.
It was not until they checked the app the next day after work that they discovered they were millionaires.
The self-employed plasterer said he has no plans to hang up his trowel just yet but will reduce his hours.
He said: “We’ve got a wedding to plan and I want to make it the wedding of Ceri’s dreams.”
They will use the cash to buy their first house and car.
Ms Hall said: “This is just life changing for both of us.
“We’ll be able to do so much that we could never afford to do. I can’t wait to see what the next year will bring us!”