My advice would be to refresh and re-hone your skills on a few less critical buildings first as like many of us making the transition from an enforcement role you are likely to find it a steep learning curve.
But to answer your question BS PAS79 will be your best foundation from which to start, read in conjunction with the CLG guidance on care premises. PAS 79 does contain both the methodology and a suggested report template which many businesses have adopted.
For revision purposes CIBSE Guide E and LPC Design Guide 2000 are all good documents that bring together most aspects of fire safety in a readable way. BS9999 is another essential read but very heavy going because its so disjointed.
PS- Dont forget to also produce a written emergency plan.
