In all seriousness, I'd buy a house for cash. Nothing too flash, just somewhere like where we live now only with a garden.
Then I'd (delicately) try and pay off the mortgages of my family and some of my friends.
Then I'd put some in a high interest account to give me an income of around £500 a week (which is what I earn now).
Then I'd give up work (having first worked my notice) and go on a cycle touring holiday for weeks on end.
I might revive some old hobbies that I no longer have time for. I'd love to get back into brewing my own beer, but this time with more than just some plastic buckets, a boiler and a mashing bag.
I'd probably treat myself to some interesting guitars and a nice road bike. Wouldn't bother with a new car though, they bore me to tears.
If I'm being absolutely honest, I probably would buy a big bag of weed to celebrate my win.
In short, If I won a lot of money I'd just do the same things as I do now, only more so.
Oh, and I might be tempted to buy my own articulated lorry, park it outside the house and watch it rot. (I've had a bad day at work ...)