Yes, Martin Lewis MSE has given a round up of who is doing what. I went to Morrisons today to stock up on Christmas veg for 10p a bag. Aldi, Lidl and Asda are even cheaper at 8p but further away from me.
Tesco's have bags of fresh carrots, sprouts, parsnips, 2kg bags of potatoes, red cabbages for 15p per bag if anyone is interested. Not just for Clubcard members. I assume the other supermarkets will, or have, done the same.