My local 'Costcutter' convenience store has been charging £1.35 for a 4 pint container of milk for some years. I very much doubt that any farmers receive a higher price from Costcutter's supplier. I'm lucky in that I don't have to buy from this particular store, but it is surrounded by a lot of pensioners social housing, who have mobility problems and therefore tend to use their local shop.
My Father in Law gave up milk production years ago after the quota system was introduced, as this did not allow him to make a profit from his small herd, especially at the price received from the wholesalers!