as you're non-registered here ,if the dno have to get involved for metering alterations,increase in capacity etc the work will need inspection,payment of fees,paperwork etc.
there's also something on the way to (try to)prohibit non-registered sparks working altogether-i don't know if it's up and running just yet
-RECI will be able to tell you
there's quite a differences in the wiring rules as well