Countries never invaded by the British are:
Andorra, Belarus, Bolivia, Burundi, Central African Republic, Chad
Republic of Congo, Guatemala, Ivory Coast, Kyrgyzstan, Liechtenstein
Luxembourg, Mali, Marshall Islands, Monaco, Mongolia, Paraguay
Sao Tome and Principe, Sweden, Tajikistan, Uzbekistan and Vatican City
Note: Some of these countries are new so give the Brits some time to plan more invasions.