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

Here is Why You Need An Adapter

The outlet and plug type used in Great Britain is G and in New Caledonia are C and F. This is how they look like.

New Caledonia

In New Caledonia, outlets of type C and F are in use.

Type C

Type F

Great Britain

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

Type G