You Do Need power plug adapter while traveling from Channel Islands (Guernsey & Jersey) to East Timor (Timor-Leste).

Here is Why You Need An Adapter

The outlet and plug type used in East Timor (Timor-Leste) are C, E, F and I and in Channel Islands (Guernsey & Jersey) are C and G. This is how they look like.

Channel Islands (Guernsey & Jersey)

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

Type C

Type G

East Timor (Timor-Leste)

In East Timor (Timor-Leste), outlets of type C, E, F and I are in use.

Type C

Type E

Type F

Type I