All plug sockets have a standard height in the UK.
Here we see min 45cm from floor and 120cm max. Sockets are always needed if an appliance or electrical item is seen in the scene with a wire.
70-80cm away from table tops.
75-100cm away from Kitchen tops.
Spot lights are typically at least 150cm apart.
See to the left shower heights.
All units differ in sizes due to client specifications but general spacing and sizes can be seen below.
A great website to reference is: https://www.dimensions.guide/
Obviously window heights vary but an indication as to size and location can be found here to the left.