If your ancestors were married in a Church the Lancashire BMD results page tells you which church.
See if the marriage register images or transcriptions are available by:-
Checking the holdings at LFHHS Family History Research Centres at Chorley or Oswaldtwistle
go to Ancestry, FamilySearch, local Online Parish Clerks, FreeREG or other genealogical websites
Save the cost of purchasing a certificate from the GRO.