If you need to certify a document for use in the United Kingdom, you can use a commissioner of oath instead of a notary. For example, if you need to produce a copy of your passport, utility bills, your photo or your signature for any application you send to the UK authorities or organisation, you can take your documents to any solicitor, who can certify such documents. Statutory fee of a commissioner of oath is £5.00, if the commissioner of oath issues a certificate, the statutory fee for such work is £10.00. Estate agents, accountants and some other professionals can act as a commissioner of oath too. The exact requirements are usually explained in guidance notes of an application. Solicitor or legal executor can also witness your signature on an affidavit or a sworn statement.
However, for the documents which are to be outside the UK, you MUST use a notary, as in most countries certification of signature on the legal document, as well as certification of passport copy or any other personal document is a notarial act.
Documents like a power of attorney, authorisation, parental consent, spouse consent, inheritance acceptance (renunciation) declaration must be certified by a notary, in some cases by a scrivener notary. Scrivener notaries have a linguistic degree as well as law degree, they are qualified notary with working knowledge of another language (French, Italian, Spanish, Russian, German, German, Greek, Polish, Portuguese) and provide notarial services in context of international transactions.
The notary should be able to confirm that the document complies with relevant laws, drawn properly and signed in good faith without any coercion by a person of sound mind and clear memory with the necessary amount of legal capacity. That the signatory of the document fully understands the meaning, conditions of this deed and its legal consequences and that the text of the document fully corresponds with his/hers own free will and there are no grounds, preventing the execution of such deed. As this is more complex work the fee is higher and usually discussed with a client before hands.