do i need to be registered to have a website where ppl enter to win prizes?

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i have an audacious idea of a way of making a bit of extra cash online... im just wondering whether i could run a website where people enter for a pound, and at the end of the week/ month or whatever, all people who have paid go into a prize draw, with the winner receiving a prize? i would clearly state the prize obviously so they no what they are entering for... annyone any ideas? thanks