Certificates will give you more information such as names of parents and or dates of birth so that you can track down earlier records of these people and their ancestors.
Likely partner Ben's birth...
Name: FITZGERALD, Benjamin James
Registration district: Croydon
County: Surrey
Year of registration: 1982
Quarter of registration: Apr-May-Jun
Mother's maiden name: Wallace
Volume no: 11
Page no: 2416/X1475
This appears to be the marriage details...
Groom: FITZGERALD, Michael P E
Bride: WALLACE, Gillian M
Registration district: Croydon
County: Surrey
Year of registration: 1978
Quarter of registration: Jan-Feb-Mar
Volume no: 11
Page no: 1078
There are several possible births for Michael (marriage cert should give you age)
FITZGERALD Michael P England Leicestershire, Leicester 1947
FITZGERALD Michael P England London, Chelsea 1951
FITZGERALD Michael P England London, Lambeth 1952
FITZGERALD Michael P England London, Hackney 1956
FITZGERALD Michael P England Surrey, Surrey South Western 1956
FITZGERALD Michael P England Middlesex, Willesden 1956
FITZGERALD Michael P E England Sussex, Horsham 1957
FITZGERALD Michael P England London, Kensington 1958
FITZGERALD Michael P England Warwickshire, Birmingham 1959
FITZGERALD Michael P England Essex, Essex South Western 1960
FITZGERALD Michael P England Essex, West Ham 1960
FITZGERALD Michael P England Lancashire, Manchester 1960