The no deposit bonus offer requires only to register a new account. Some brands ask to register credit or debit card just to verify that your details are real and correct. That's all. Once everything is done your account will be funded with a free bonus and you can start to use it immediately, as you wish.
Sometimes the restrictions of these promotions are limited to the permitted games. In general you can use the offer to play slots, video poker, video roulette, scratch cards, instant wins, video blackjack and many other interactive games. You can not use it only for live dealers.
When you see such type of deal it's good to know what's the maximum. Sometimes a um of £10 or £20 is much bigger than only £5, and you can see it easily. When you get big bonus you have a bigger chance to win and play more. At the very beginning all casinos had only £5 free bonus, but in the last 3 years we see a tremendous growth of the maximum amount of free casino chips.
It allows players from UK to enter directly the most attractive casino sites without any deposit and play for real rewards. In other words you can use these offers to get real free Vegas casino bonus and play for real winnings, without any transfer from your credit card or bank account. It's really free, there are no hidden tricks that ask for a deposit.
Beware only about the withdrawal of your winnings, it may require to make a deposit or wager the amount at least 3,5,10 or more times before withdrawal the won money with a free bonus.