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

Here is Why You Need An Adapter

The outlet and plug type used in Canary Islands are 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

Canary Islands

In Canary Islands, outlets of type C, E and F are in use.

Type C

Type E

Type F