The power to make a community order or youth community order is not exercisable in respect of an offence for which the sentence—
(a)is fixed by law,
(b)falls to be imposed under section 51A(2) of the Firearms Act 1968 (c. 27) (required custodial sentence for certain firearms offences),
(c)falls to be imposed under section 110(2) or 111(2) of the Sentencing Act (requirement to impose custodial sentences for certain repeated offences committed by offenders aged 18 or over), or
(d)falls to be imposed under any of sections 225 to 228 of this Act (requirement to impose custodial sentences for certain offences committed by offenders posing risk to public).