The MGRV8 shares its door mirrors with the Rover Metro / Rover 100. The mirrors are universally handed so will fit either side. Also the Metro mirrors are usually colour coded so you may find a pair to match the colour of your car ……. which I am now on the lookout for.
Many mirrors on the Metro are electrically adjusted and heated so could possibly be adapted to suit the MGRV8 ……. although I think I will give that a miss.