The company name cannot be the ‘same as’ or ‘too similar’ to a name that is already in use, and it cannot be offensive or misleading in any way.
There are a number of words and expressions that are considered 'sensitive' if they are included in a company name. If you wish to register a name that contains any sensitive words or phrases, you will have to get permission from the Secretary of State at Companies House or the relevant regulatory body for the word you wish to use.
All company names must end with 'Limited' or ‘Ltd’, with the exception of some non-profit limited by guarantee companies. All LLP names must end with 'Limited Liability Partnership' or 'LLP'.