There are virtually NO marriage certificates pre 1878 - what you have are entries in some Parish reg (the exceptions are for marriages in non-established churches but the dominant Methodists still married in Parish church until late 19th C and even then still quite rarely in Chapels)
The Parish Register should state if a minor (ie under 21 - in practice I find that those below 20 will generally be noted as such - maybe they argued that the party was in their 21st year) but no date of birth will be given - post 1757 you will find status of parties (widow etc), and names of two witnesses (earlier regs often had a farm or residence as a distinguishing mark agaianst the entry) - later in 19th C you should get father's name and profession but you can get all this info from the filmed transcriptions of Parish reg