I strongly disagree with bigtimer. There are some fantastic free bet promotions out there to suit whatever level of betting you wish to do. If you are looking for something small I'd recommend boylesports. If you deposit and bet £20 of your own money they will then give you a free bet of £20.
If you are looking for a higher promotion I'd recommend waiting until the weekend and opening an account with bet365. On weekends bet365 up their sign up offer from £100 to £200.
It's true that there are wager requirements involved and is therefore important that you thoroughly read the terms and conditions before depositing any funds. But there are loads of online sportsbooks offering sign up deals and many of them are great value.
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