I've been thinking about this recently as I've just invested some savings in a sizeable amount of premium bonds, so theoretically should be due the big one soon 😜
I'd give away £100k each to my Mum, Dad brother and sister, and put £50k in the bank for each of my 2 DC, so that's already half gone.
I've drawn up plans for a loft conversion and a kitchen diner extension, and can only realistically afford the loft now, however if I had this money I could do both immediately for £150k.
I'd take my DC plus our Nanny, my parents, siblings and their families on an all expenses paid Disney Florida villa holiday. I'd budget £30k for 13 people to Disney, including flights and accommodation.
I'd keep working, as I love my job and it pays well, so I'd probably pay the maximum overpayment to my mortgage each year until the fix is up £50k per year for the next 4 years = £200k.
I'd probably just keep the final £120k as emergency money in a high interest ISA.