You Do Need power plug adapter while traveling from New Caledonia to Northern Ireland.

Here is Why You Need An Adapter

The outlet and plug type used in Northern Ireland 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

Northern Ireland

In Northern Ireland, outlets of type G are in use.

Type G