pening, although it's handy to have Part P, it's far from essential. Many independant installation contractors get by without it as crazy as it sounds, and they still earn a good living. As I said, there are some out there that feel that the cost of the course is prohibitive.
Yes, I am and I've got over 30 years experience in domestic installation and practice in an employed and self-employed capacity. I also lecture part-time on electrical installation at the local FE college
As Buenchico says, The Answerbank doesn't do instant messaging. I'm only on here today because I'm at a loose end over the Bank Holiday!
Buenchico has provided a comprehensive explanation of NAPIT and STROMA.
Third-party certification is straightforward but be aware that a competent certifier will take his or her time checking the property. You need to discuss this with the certifier on the phone BEFORE you appoint them to do the job. A competent certifier will check your property from top to bottom before agreeing to issue a certificate. I won't give you an estimated time to do the job as it depends on the size of the property, the condition of the wiring, access issues to lofts, external buildings etc and a whole host of other things.
You would think that the cost is based purely on the certifiers hourly rate plus a top up for his experience. However, there is far more too it than that. The instrumentation needed to provide figures for entry on the certificates are expensive and need expertise to interpret. Furthermore, the instruments require independant calibration relatively frequently and this costs the certifier money. The regular tinkering around with the wiring regulations also means that he has to be up to date with his knowledge usually by compulsory courses that again cost money.
You've not given us any information about the property, which would have been helpful as it might be very pertinent when considering the work that needs to be done. Bungalows for example, are generally much simpler to certify than a three-storey terraced property or HMO's!