Hi New Venture welcome to the Forum .
My background is Industrial , commercial, domestic but I do understand that , although basically a simple concept of 1 ph, Twin/Earth radial circuits with the odd 2 way thrown in , Domestic is really another world to what you are used to .
Its more regulated than anything in our trade TBH.
Can I ask the following questions ?
I presume you have the basic qualifications for being an electrician ( Given your background) ?
Are you up to speed on domestic work ? Bonding etc ,
Although many do not bother to join a scheme , we are supposed to be competent under Part P of the Building Regs and a scheme is the only way to prove this really.
More customers are looking for a registered spark these days .
You need to be registered to sign off new build work to Local Building Control .
You are supposed to certify & register all your work with the scheme who will guarantee same . ( Most of us have no interest in that side whatsoever)
To join a scheme ( who basically just want your money) you need the following :-
1 Prove to be competent.
2 Have basic quallies for sparkying .
3 Have recent job to show .
4 Own test instruments Loop Imp / Megger / RCD / continuity.
5 Public liability insurance.
6 Have G&Gs 2382 for 17th edition Regs
7 Own latest edition of Regs
8 Own Electricity at Work Regs 1989
9 A written H& S document
10 Provision of written quotes
11 A complaints log
12 A good knowledge of Building Regs
13 Relevant test & inspection documetation .
I doubt you need to do a 17 day course given your background , ( although that is exactly what they were designed for NOT for local milkman to become a sparks in 3 weeks)
Anything else just post on here.
Edit :-
As Murdock says , try to stick with what you know and are good at , commercial / industrial. and Domestic as a second string.