The local council cemeteries section will have ledgers in which the layout and allocation of plots are recorded for municipal cemeteries. Those owned by different religious groups SHOULD have the information but might be very variable.
Ive been doing family history. Every church Ive been to trace graves has had a grave yard plan held at the church luckily, but not all churches hold the records, some are held by the council.
Civic cemetaries all have excellent plans and usially good computerised alphabetical index of burials.
The Monumental Inscriptions in many Parish Graveyards have been recorded and indexed/published by local family History Societies as part of their reason for being registered charities, if you contact your local county family history society they will have a list of their completed and ongoing MI projects.
don't mistake a burial register of a Parish for a recording of the Monumental inscriptions on the gravestones or for the grave book , which is a DIFFERENT record and records the numbered burial plots.
I visited a couple of cemetaries recently looking for the graves of relatives. At the first I approached a cemetery worker who took me to the office where they kept a plan of all the graves. Once I had given him the name and date of death he quickly found the number of the grave on the plan and then took me straight to it. At the second cemetery I couldn't find anyone around so I found the number of the local council on my mobile phone. They put me through to the relevant department (Parks and Cemeteries I think) who also have plans. After giving the very helpful lady whatever details I could she told me the number of the grave I was looking for. Then I found a cemetery worker who took me straight to it.