Compatibility summary
You will need a travel adapter in Benin; plug types used there differ from United Kingdom.
Plug comparison
United Kingdom plug types: G
Benin plug types: C E
There is no common plug type between United Kingdom (G) and Benin (C E). You need a travel adapter.
Voltage comparison
United Kingdom: 230V, 50Hz
Benin: 230V, 50Hz
Voltage difference is within a range many devices tolerate; check your appliance label.