You Do Need power plug adapter while traveling from Switzerland 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 Switzerland are C and J. This is how they look like.

Switzerland

In Switzerland, outlets of type C and J are in use.

Type C

Type J

United Kingdom (UK)

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

Type G