This bonus is open only to new players. Anyone who registered will automatically get £5 in his Bonus Balance. There is no requirement to deposit to get this amount. From time to time, the casino will replace this amount with 50 free spins but only on specific slot machines. Each spin is valued at £0.10.
Players who are lucky enough to win without maxing out the £5 can enchase their winnings, subject to all withdrawal rules. So if you received £5 and won £1,000, you can cash out your winnings but the initial £5 will stay in your balance. It will not be voided and you can keep on using it to play.
The caveat is that you can only withdraw a maximum of £200 if you did not make any deposit at all. And this applied to UK players. If you are not from the UK, the maximum you can withdraw is £50 if you did not make any deposit.