You Do Need power plug adapter while traveling from Palestine to Channel Islands (Guernsey & Jersey).

Here is Why You Need An Adapter

The outlet and plug type used in Channel Islands (Guernsey & Jersey) are C and G and in Palestine are C and H. This is how they look like.

Palestine

In Palestine, outlets of type C and H are in use.

Type C

Type H

Channel Islands (Guernsey & Jersey)

In Channel Islands (Guernsey & Jersey), outlets of type C and G are in use.

Type C

Type G