Grain cost have/will rise significantly even for UK grown grain as it needs to be dried before sale - that's a big expense for growers.I have to disagree about flour.
The UK is largely self-sufficient in production of grains, producing over 100% of domestic consumption of oats and barley and over 90% of wheat.
So if what HMG tell me we shouldn’t have any price hikes or shortage of flour🤞