Find yourself a retired Area fire officer..they chuck out @ 55yrs with a fat pension Quite a lot go on to work in hospitals etc. as fire safety officers They should know all the regs
Its not as simple as knowing the regs, the OP cannot or will not comply with them due to his current layout and his only hope is to negotiate/add counter measures to get his approval although as you say it may be worth taking an independent inspector along with you. It may even be worth approaching an independent inspector (rather than local authority)although I suspect you'll have pay the fee up front in this scenario.