On my first assessment, I did a consumer unit swap, I informed the client I would like to use this as my site visit. They agreed to pay for notification fees and materials, my labour was free.Is that not the OP's problem? As you say, he is going to have to notify, and pay notification fees, at least once in order to get registered, and then he has to pay all the (direct and indirect) costs of notification.... If you own home or have friends/relatives with domestic properties? This work can be carried out there, the work will require notifying, so there will be that fee to consider.
What we want is not always what we get, if he is operating as a domestic electrician there is going to be occasions that all that needs notifying is electrical work. Plus as a business it is always good to be able to advertise that you operate in away that notification can be made by you and that with that notification a 5 year warranty is attached. I don't think building controls other an automatic five year warranty.Given that, as has been said, most/all of the work he wants to do could be done under a single notification, I'm far from convinced that the 'getting registered' route would be cost-effective for him. Even if he had to pay for two or three notifications, that might still be less expense than the registration route.
If the OP is serious about wanting to become a scheme member, he needs to abide by there specification. But it is worth looking around as not all ask for the same.
The document below seems to suggest that the work assessed, is that of the type that is deemed notifiable. That is why it is worth the OP calling them.The above comments are based on one assumption - do I take it that ELECSA will only accept job(s) involving notifiable work as the job(s) they inspect?
This document would be useful for those interested.
http://www.elecsa.co.uk/Documents/Public-Documents/Contractors/ELECSA-Part-P-Guide-(Web)-06-15.aspx