We do not provide a certification service. We can provide official duplicate documents, orders can be placed on the online store.
It may be of help to visit https://www.gov.uk/certifying-a-document
If you wish to obtain certified copies, you can do so by having a document certified as a true copy of the original by getting it signed and dated by a professional person, like a solicitor.
If you are going to use your document overseas, you may need to have it legalised before it will be accepted. You can find out more about having your document legalised at https://www.gov.uk/get-document-legalised.