Willhub, if you plan on paying off your credit card every month, them your idea of getting one is fine, the problems come when you stop clearing the balance monthly, or over indulge.
Sticking to budgets is tough, but a great life lesson for when you eventually get a mortgage/rent other then from parents)
If you shop around there are some good credit cards that provide some nice benefits. Telcos credit card allows you to earn clubcard points that can be used for all sorts of fun, Santander do a 123 credit card and account that offer cash back (monthly charges apply to both) but depending on your spending you can easily earn money on them.
Other things to consider are opening ISA accounts and commit to paying in to the, by standing order, and just don't withdraw from them. Another is bond saver accounts, once you get a certain amount of money pop it in to bonds for 1-3 years and if you w/draw it you get no interest, so it's kind of encouraging to leave your money there etc.
Lastly, and the most extreme option is get a loan, then get your parents to put the money in to a savings account/isa on your behalf. Yes this will ultimately cost you money, and the only benefit here is it provides you with a commitment that you are tied in to and will benefit your credit rating if you stick with it, and punish your credit rating if you miss payments etc. I would only recommend the last option if you really want to improve your credit rating, and cannot trust yourself not to spend the money/overspend etc.