Compatibility summary
You will need a travel adapter in Marshall Islands; plug types used there differ from United Kingdom. Voltage differs by more than 20% — a voltage converter may be needed for some appliances.
Plug comparison
United Kingdom plug types: G
Marshall Islands plug types: A B
There is no common plug type between United Kingdom (G) and Marshall Islands (A B). You need a travel adapter.
Voltage comparison
United Kingdom: 230V, 50Hz
Marshall Islands: 120V, 60Hz
Voltage converter recommended (United Kingdom 230V vs Marshall Islands 120V).