No it wouldn't!
If you do any work especially for paying customers it is your responsibility to do the job safely and in line with all regulations. (You could be held accountable under law if you don't)
Remember, that's ALL regulations, not just the electrical ones you learnt 40 years ago.
If you cut holes in joists, or position outlets, all this has to be in-line with building regulations, the C&G or 18th edition only extends to the electrical aspects, not the whole job.
The building regulations specify many aspects of the day to day work of all electricians - just not the electrical bits.
Part P specifically mandates that certain work is notifiable to the local building control, this includes electrical work in kitchens, bathrooms, new circuits etc. etc.
It is actually an offence in law not to notify.
Insurance generally covers you for errors (put too big a hole in a joist which then collapses etc) but won't necessarily cover you if there is systematic breaches of regulations, as this would be considered deliberate, it also won't protect you from flagrantly breaking the law.