Third party inspections always carry more weight in a court of law.
Should a scaffolder take on the responsibility of inspecting scaffolding ?
I think not, Scaffolders these days have enough on thier plates complying with all the regulations heaped upon them without having to "sign off" structures as safe.
Before signing documentation as to the "safety" of a structure I would advise that you obtain "Professional Indemnity Insurance" to cover your *rse, in the case of any NEGLIGENCE procedures being taken against you.
Make no mistake your employer will state,in the case of any accidents,
that it was you who signed off the structure as safe for use