I would take my three brothers, their families, and as many friends as I could persuade for a riotous week at the Bitter End Yacht Club, on Virgin Gorda, in the dankest glummest time of the year (February or March). This is a really good place because the sky is blue, the coral is bright, the trade wind blows, and they have all these boats ready on the beach for impulse sailing.
I would try to pay off my families' and friends' mortgages and debts, if they agreed, so we could all start out afresh, and make whole new financial messes of our lives.
I would go sailing, but it would not be a holiday so much as a round- the-world sailing trip in my new boat. I'd have to go to Pitcairn. And the Galapagos. And Tahiti. And follow Captain Cook round the Australian coastlines. And dodge the ice in Greenland.
If you have unlimited funds for travel, you might as well stay based at home near your friends. I might have some interesting holiday homes - a Venetian palazzo, a deserted castle - but would insist on them being used, maybe for school trips. I have a serious bee in my bonnet about the need to show children something other than shopping malls and motorways and suburbanised countryside; the new novel is about a teacher who takes a pack of 11-year-old kids to Venice, so it would be symmetrical if I gave the palazzo for real kids to use. It would be big enough, and scruffy enough, to suit them nicely.
I would go on writing novels. Couldn't prevent myself. It would be fascinating to see whether I could wean myself off writing opinion columns; pontificating is addictive. Perhaps I could buy a newspaper and interfere horribly with its editorial policy. That should be fun.
I certainly wouldn't carry on playing the lottery. That would be very, very sad behaviour.
Libby Purves's latest novel `More Lives Than One' is published by Sceptre, pounds 16.99. She presents `Midweek' on BBC Radio 4Reuse content