The UK mains supply is 230-240V. Mains electricity is AC (alternating current)
The electricity in the mains supply switches direction 50 times per second. But this is too fast to see so lights don’t appear to flicker… although they are, 50 times every second!
The larger the current (faster the electrons travel), the greater the friction produced. Friction produces heat. This heat is used for kettles, cookers, irons, etc.
This video explains about Mains Electricity
The National Grid
National Grid = Power station > step-up transformer > pylons > step-down transformer > homes
Electricity is produced in power stations
It is transported along pylons at very high voltage (400,000V)
The higher the voltage, the lower the current
The lower the current the smaller the heat (energy) loss
The high voltage is not safe for domestic use, so the voltage is stepped-down to 230-240V
This video explains about transformers and step up and step down electricity