You cannot incorporate a company using any name you like. Some names are prohibited (for example, those which suggest a connection with the Government or the Crown) and names will not be allowed if they are too similar to the names of existing companies.
In 2013, facing more than 4,000 applications for names per month which required review, the Government acted to reduce the number of restricted names. A new list of restricted names was released, with names such as National, United Kingdom, Register and Authority being removed form the list of 'sensitive' names. The revised list can be seen here.
Companies House provides guidance on the rules for choosing names for new companies. Don't forget to check that the associated Internet domain name is available as well. Different rules entirely apply to the registration of domains on the Internet and the regulations also vary from country to country. For example, some countries will not allow the country's domain suffix to be registered to a domain unless there is an active trade mark and/or trading presence in the country.