Your document must be certified by a professional person or someone well-respected in your community (‘of good standing’). You could ask the following if they offer this service:
bank or building society official
councillor
minister of religion
dentist
chartered accountant
solicitor or notary
teacher or lecturer
https://www.gov.uk/certifying-a-document
又或者去IMMD 俾$140 Print 一份出生登記記項的核證副本 (所謂正本)