What anyone can do in a kitchen under SI2006 Non-Notifiable Works is quite limited.
You can not...
- Add a new final circuit
- Add a new wiring accessory (eg, socket)
- Install a new CU with all new circuit breakers (see note below re enclosure)
You can...
- Perform maintenance (this one is very grey, if it is to correct non- BS7671 there is little problem)
- Replace wiring accessories
- Replace cabling for a single "circuit" (note BS7671 definition of a "circuit" is defined as protected by a CPD, so not just a single cable; CPD being circuit protective device such as MCB or CPD)
- Replace any damaged enclosure (including CU)
- Replace any protective device (such as RCD, altho an issue is testing the new one properly re 1/2x 1x 5x trip times etc)
The reason for "can not" is as much a DIYer would not have the required test equipment with calibration certificate, some do but not all. The most critical of these is actually an RCD tester - that the protective devices DO in fact work re electrocution in a "special location" re water and electricity. It would have saved many lives over the years and many many sparks until Part P never had the kit (they actually shared it between mates, seriously and not illogical really).
Go to ODPM website and download SI2006. Skim read it, then read it again carefully.
The person may well be qualified (C&G 2382 & 2392 which you can check). However he is not registered with an appropriate scheme (which may be down to cost or failed an assessment). He may may not have test equipment in calibration. He may have gone industrial based on his C&G, JIB card etc and not bothered with domestic anymore, who knows.
The problem is:
1 - If he can't notify the job, you/he will AND have BC come and inspect AT YOUR COST
2 - He may walk off without any notification, you need to then PAY to Regularise it
Regularisation can be easy or DIFFICULT depending on the LABC. They may accept a PIR, or cable tracing, or require cables exposed and so on. The DSA publish guidelines, but some have a bee in their bonnet about stripping everything out. Others are more practical - it can depend on what they find (if workmanship has faults they will soon suspect cable routes, sizing, grouping factors and so on).
Frankly I am with industry - if the guy has sufficient C&G and 1yr experience then nothing else should be required. The problem is domestic is with Part P - SI2006, which leaves the OP with a problem - the guy has plain deceived you.