Maybe you read my thread wrong, I started this thread to see what I needed to sign off an installation as I have heard different things
What ruston said really. If you have carried out non-notifiable work as a "competent person", then you can test and issue certificates for that work. If you are carrying out notifiable work, such as supplies to outbuildings, CU changes, new circuits back to the CU, extensions to kitchen/bathroom wiring, etc, then you either notify LBC in advance or pay up and join a scheme.
We keep answering these questions, when really the search facility is your friend here!