Your main fuse, and who owns it
Where the supply enters your house there is a service cut out with a fuse in it. That fuse sets the absolute ceiling on what the property can draw. Common single phase ratings are 60A, 80A and 100A.
Here is the part people are rarely told: that cut out does not belong to you, and it does not belong to your electrician. It belongs to the distribution network operator, which in the north of Scotland is SSEN. No electrician can lawfully change it. What we can do is establish what you have, work out what you actually need, and support the application.
Simultaneous demand is the real arithmetic
What matters is not how much electricity you use over a year. It is how much you want at the same moment. A car charger, an electric shower, an induction hob, a heat pump and a home office all asking for current at six o'clock on a February evening is a completely different proposition from the same house in 1987 with an immersion heater and a kettle.
Whether any given addition needs a supply upgrade depends on your assessed maximum demand. It is not automatic, and anyone who tells you a charger or a heat pump automatically requires one has not done the assessment.
Three options, and a rewire is not one of them
Once we know the supply rating and the demand, there are three honest routes. Load management, meaning a smart charger or controller that curtails automatically so the total never exceeds what you have. A supply upgrade application to the network operator. Or a board with the ways and the protection to carry the new circuits properly.
Rewiring replaces the cable inside the house. It does not change the supply coming into it. If capacity is your problem, a rewire is an expensive way to not fix it.
Why this bites in Kingswells specifically
Kingswells sits on the western edge of the city, separated from Westhill by the AWPR, with Prime Four Business Park on its doorstep. It is a commuter and hybrid working suburb of driveways and garages. That means car chargers, garden rooms, garage conversions and home offices stacking up, one at a time over several years, on installations designed around what a household wanted in the 1980s. Nobody plans that load. It accumulates.