Oh no it won't...
"All this could be done and would have no effect on operational Policing. This would more than likely return monies back to front line."
It would return nothing until all the costs associated with setting it up had been amortised; of course any additional non - personnel related costs would have to be covered as well.
From where, exactly, do cost savings come? Unless existing HR (and other) departments are grossly overstaffed (which may or may not be the case) any new super - system will need the same number of people operating it, less perhaps a few managers.
In addition although basic HR functions may be common to all services the different services do have different things to record about their employees, so either any individual record would have a load of blank fields not relevant to the function or different services would have completely different sections of an overall software package, which would mean a potentially underused system.
The plan to reduce the number of Fire Control Centres went horribly wrong at tremendous expense, and the amalgamation of Police Forces in Scotland has not been without its problems. Reducing the number of Police Control Rooms is not without its risks (OK that isn't a back office function) as local knowledge vanishes; I have tried to report a couple of minor problems to my local force and their mapping system was unable to even vaguely identify locations by road number.
"More IT" is not always by definition an improvement.