Most of the electrical work is invisible and irreversible. Two decisions matter more than the rest: how much supply you have, and where the cables run.
Size the supply before choosing appliances
A single-phase 16 A connection is a common rural offer and it will not run an instantaneous water heater, an induction hob and a heat pump at the same time. Knowing the available supply first changes the appliance list, not the other way round.
Where the supply is limited, load management — a controller that sheds the water heater while the hob is on — is cheaper than upgrading the connection. Ask for it at specification, not after the first tripped breaker.
The consumer unit needs room to grow
Fit a unit with spare ways. A solar inverter, a battery, an EV point or an outbuilding each need a way, and a full board means an additional enclosure bolted somewhere it does not belong.
Residual current protection on all final circuits is now standard and worth insisting on regardless of local minimum. In a building with an outdoor socket and a metal frame, it is not a formality.
Sockets: count them, then add four
Small houses are socket-poor because the wall length is short. Count what you plug in on a normal evening — router, laptop, lamps, chargers, kettle, vacuum — and place them where those things live rather than at even spacing.
Two at worktop height in the kitchen, two at desk height, one beside each side of the bed and one on the terrace is a reasonable floor. Every one of them is a drawing note and an extension lead if it is missed.
Earthing a steel-framed building
A steel chassis is a conductive structure that has to be bonded properly, and the arrangement differs depending on whether the house is on a mains connection, a generator or an island inverter. This is a point to have documented, not assumed.
Keep the test certificate. It is the document an insurer asks for after any electrical incident, and it is what a buyer's surveyor looks for.
Plan the low-voltage side too
Network cable to the desk, a route for an external aerial, speaker cable if you want it, and a conduit from the consumer unit to the roof for future solar. All are trivial before the walls close and disproportionate afterwards.
Pull a spare draw cord in every conduit. It costs nothing and it is what makes a future change possible without opening anything.