You Do Need power plug adapter while traveling from Wales to Laos.

Here is Why You Need An Adapter

The outlet and plug type used in Laos are A, B, C, E and F and in Wales is G. This is how they look like.

Wales

In Wales, outlets of type G are in use.

Type G

Laos

In Laos, outlets of type A, B, C, E and F are in use.

Type A

Type B

Type C

Type E

Type F