This is like trying to claim bioethanol is somehow carbon negative.
It's broken from a farming standpoint (and we're a nation starting to face issues with production. Notice how I say starting not we're starving there's several world's of different yet)
It's broken from an economic standpoint because you're going to try and take on the whole of Asia who could crush you in a single shipment.
It's broken from a mindset perspective. British wine may be one that grabs interest over here like British vodka. But people will not pay 10x or more for British rice. It will be seen as a stupid concept or idea.
It's broken because again... Who in Britain is clamouring for more rice options? This is a product type which is already over saturated at the normal supermarket, let alone the choices when you're willing to shop online.
If there's no discouragement to projects like this idiots will run the land into ruin, lose a lot of money. Drive away needed capital from farms looking to turn around their fortunes and damage the sector.
I'm not saying British farms are about to collapse and we're all about to starve here, but the sector is struggling.