Please note that a UK marriage/birth/death certificate issued by the General Registry Office cannot legally be photocopied as it is subject to Crown copyright. If a photocopy is presented for an apostille, the Foreign Office will refuse to apostille it as this is how they protect and enforce crown copyright on behalf of the British government, if you look at the small print at the bottom of the certificate you will see the official reference to “© Crown Copyright”. If the marriage/birth/death certificate is issued by the UK General Registry Office then a new certified copy issued by the General Registry Office would need to be ordered, which can be done here:
Please note that this means that only a certified copy issued by the General Registry Office can be notarised and legalised, not a photocopy. If the document needs to be notarised, then the (original) certified copy issued by the General Registry Office/original certificate will be permanently altered by the notarisation process as it will be attached to the notarial certificate using an eyelet (a small hole punch reinforced by a metal ring) and stitched to the notarial certificate, bound by the notary’s ribbon and official seal.