Indeed - similar with my LA, and I suspect many/most others.Also, for my LA, they list fees for regularisation - basically if you fail to notify in advance, then they charge an extra 50% and allow you to notify afterwards. If someone's failed to notify in advance,
However, that relates to a different situation from what we are discussing here. As you say, these 'regularisation' procedures are to deal retrospective with a situation of prior 'failure to notify'. However, in the OP's case, there has not been any such failure, since the electric work was 'notified' (implicitly, if not explicitly) in his Buildings Regs application.
Kind Regards, John