Hi UKengQatar,
Just like the EU citizens, UK citizens would also be entitled to a 1mnth extension.

Having mentioned the Americans; are they exempt from paying any fees on arrival? Do they also receive 1 month + the extension or more :D

If the historical and political context of the British colonial territories were translated into mutually feasible combinations - then this would imply that Britain should issue visas on arrival to all prior dominions.