Capital One will give a credit card to most people, even those with poor credit ratings. The interest rate can be quite high and the initial credit limit is usually fairly low but their cards may be suitable for people who find it hard to get credit elsewhere or people who don't want to be tempted by high credit limits: http://www.capitalone.co.uk/creditcards/cards. jsf
Most companies will give you a small limit to start with anyway, but they will also allow you to set your limit at what you feel is reasonable- you don't have to take their offer.
Don't expect a limit of less than �1000 though. To get that you need to get a poor credit rating!!
You can buy what seems to be a credit card at supermarkets. It's like the gift cards they sell, you buy a certain amount, but you use it like a credit card.