I rather think that prices of a lot of British produce will rise, if there's the predicted lack of harvesters from elsewhere in Europe.

And it seems pretty likely that the value of the pound relative to other currencies is liable to go through the floor in a No Deal Brexit. That would inflate the price for any imports from anywhere. Even during these endless two and a half years in Limbo it's gone down to near parity with the euro (£1 /= €1.11).