I entirely agree with Ethel's answer.
As long as you are careful to pay the balance off in full each month (you may be able to set up a direct debit so that this happens without fail), the credit card will help you build up a credit rating by proving you can meet the terms of a credit agreement, will give you additional protections on large purchases, and will usually have additional benefits like cashback or a reward points system, all without costing you anything.
Shop around for a card which gives a reward you will find valuable. If your credit rating is not that good at the moment, some offers may not be available to you, and you should be careful not to make too many applications at around the same time, as this can temporarily damage your credit rating.
Acting now to improve your credit rating should make it easier to access better deals and rates when you come to apply for a mortgage in the future.
Also, very importantly from a credit point of view, especially if you move around a lot: make sure you are on the electoral register. Write to the local council as soon as you move in somewhere - don't wait for the annual canvas forms in September/October. This will greatly improve your credit rating by providing a verifiable trace of your addresses.