Daniel Elsworth
Any Certificate you recieve should be provided by an electrician via an approved scheme. The NICEIC, Napit and Elecsa are the most common and you can check on their websites for registered electricians, however these are schemes a contractor can be part of to prove competatcy and standards and are not mandatory requirement. It is the homeowners resposibilty to check that an electrcian is competant to carry out the work. Having said that if the tradesmans work is not up to standards you can report them to trading standards and Health and safety executive.