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

Here is Why You Need An Adapter

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

Equatorial Guinea

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

Type C

Type E

Great Britain

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

Type G