Will my employer / local authority / insurance company / environmental health officer accept the certificate as proof that I'm competent?

They certainly should! We've trained people from all manner of organisations in the past, including staff from local and national government, large companies such as the BBC, Shell, educational establishments such as Leeds, Exeter and Bath Universities, Royal College of Music, Insitute of Mechanical Engineers and many schools and FE colleges etc. We've trained hundreds of people in industry (including a one-day course at Drax Power Station as well as people in companies such as Rentokil, Ikea, Argos, Jet2, Virgin, American Airlines etc). We've trained staff from plenty of government organisations such as MoD, HMRC, Police services, various Fire Services and Trading Standards. All of these organisations have examined our training course and selected it as the most suitable for their staff to undertake - their staff are now carrying out the PAT testing in those organisations.