Usually you will have an idea of what size bed or mattress you need. Often this is restricted by the size of your room or perhaps just what you are used to. Here is a handy guide to just double check the standard sizes of bed and mattresses for the UK. You'll notice that usually there isn't much difference in the length, usually the difference is in the width.
At BedzRus we have several childrens beds from specially selected overseas manufacturers who use the European size single mattress. These manufacturers include Stompa, Thuka, Parisot and Steens For Kids. Please be careful when selecting your mattress that you have the right size.