BS7671 is your first reference point:
Reg 134.2.1 requires appropriate inspection and testing, by one or more "skilled" persons, competent to verify BS7671 compliance has been met.. And appropriate certification shall be issued.
Reg 644.1 requires an EIC based on the model forms in Appendix 6 to be issued to the person ordering the work when replacing a consumer unit/distribution board..
Appendix 6 model forms include options if a single persons or multiple persons are involved in the the design, installation, testing stages etc..
Approved Document P is your next point of reference:
This document states it only applies to electrical work in Domestic dwellings! So it is NOT applicable in industrial/commercial electrical work etc..
ALL you need to do is decided if you are "Skilled" as per Part 2 of BS7671..
And are you the only one involved in the work or have others done some parts..
e.g. are you needing a single or multiple signature certificate!!
