I'd move or at least get a second home in the South of France, away from the coast, maybe in a small town. I'm a bit obsessed with the Peter Mayle Provence books, and the UK doesn't have enough sunshine and markets and the general rustic feel for me. DC would grow up bilingual.
I'd buy a newer car, probably an electric one, and set up a homestead. I adore gardening and I'd do that a lot ~in between lunching out~
I'd be on the Board of Directors for a charity or some community project. And donate to the upkeep of a library with the oldest, most interesting books I can find, and help with their archiving and preservation.
I'd roam around the UK visiting my ancestors' graves; I know of some dating back to the 1700s and would enjoy visiting their old addresses too.
I'd spread my mum's ashes at her favourite place to go on holiday abroad. Currently I can't afford to go there.
I'd play outdoor tennis a lot more often.
I'd hire someone to do all my food shopping for me (I'm very particular about the items) and cooking and laundry.