Oh I love this game too.
First, find a fantastic financial advisor.
Then...
Pay off the mortgage of my friends and family. Cash to my parents/PIL, sibling etc.
Money in trust for dc until they are older. I would lie to everyone about how much I’d won. I wouldn’t want dc to lost motivation in finding their own way. I would buy dc’s houses for when they went to Uni so they’d have somewhere clean and safe to live.
I’d get a new car, a personal trainer and shopping trip to Liberty and buy lots of lovely scarves then have someone teach me how to tie them so I look effortless like a Jilly Cooper heroine 
I’d give shitloads to charities. Top of the list would be our two local hospices.
LOADS of travelling, first class flights, top notch hotels etc. So many places I want to see.
I’d do courses in things I’ve always wanted to do - art classes, learning to use a pottery wheel, woodworking, bee keeping, photography all sorts of fun stuff!
I’d buy a holiday home in the West Country. I always wished our parents had a holiday home we could pop down to (living in a middle class bubble), I’d love to do that for our dc/grandchildren.
And on that happy note I’m going to bed and dream some more on how to spend my imaginary winnings 