You Do Need power plug adapter while traveling from Cambodia to United Kingdom (UK).

Here is Why You Need An Adapter

The outlet and plug type used in United Kingdom (UK) is G and in Cambodia are A, C and G. This is how they look like.

Cambodia

In Cambodia, outlets of type A, C and G are in use.

Type A

Type C

Type G

United Kingdom (UK)

In United Kingdom (UK), outlets of type G are in use.

Type G