I'm a bit concerned you are questioning what 'strain relief' is but you intend to be "doing a diy home installation of new ring circuits"..............
Do you intend to do the complete install yourself including testing and commissioning?
You both need to read his body of work here.To be frank, I'm more concerned that he needed to ask the question in the first place, and then proposed to wrap a connector block in 'insulating tape', than that he doesn't know what 'strain relief' means.
The man is the personification of ignorant incompetence and an utter refusal to listen to advice which conflicts with what he has already decided he is going to do.