If you are requested to provide a certified copy of an original document you maybe able to have the copy certified by a registered professional, other than a Lawyer. The organisation requiring the certified copy will usually provide a list of those professionals that they will accept. They normally include Doctors and other Medical Practitioners such as nurses, Teachers, Veterinary Surgeons, Fire Officers, Police Officers, Accountants and many more. For those that are on the list there is usually a registered body that hold a list of their registered professionals such as the following examples in the United Kingdom:
Chartered Accountants: www.membersearch.icaew.com
Veterinary surgeons: www.rcvs.org.uk/registration
Medical Practitioners: www.gmc-uk.org/doctors/register/LRMP.asp
Obviously it is probably easier and much more convenient to attend a Law Firm who may require you to provide appropriate identification. You do not necessarily need to make an appointment but it is best to confirm beforehand. There is a charge which is usually £5 plus £1 for each copy that you require so if it is one certified copy of one original document, then the cost would be £6.