You Do Need power plug adapter while traveling from Great Britain to Guadeloupe.

Here is Why You Need An Adapter

The outlet and plug type used in Guadeloupe are C and E and in Great Britain is G. This is how they look like.

Great Britain

In Great Britain, outlets of type G are in use.

Type G

Guadeloupe

In Guadeloupe, outlets of type C and E are in use.

Type C

Type E