Sainsbury's have been selling GM tomato puree for some time, in cans clearly marked as "made from genetically modified tomatoes" and initially flagged as "new". The product is cheaper than the conventional puree next to it on the shelf. The choice has been plain and clear.
We do have the choice, with a little care, simply not to buy foods containing, or which may contain, GM products. We do not need mass-market processed foods; we can do a little more home cooking, and can buy certified organic products such as flour and other cereals, butter, pulses, dried fruits, at not so very much higher prices.
I am more inclined towards getting what we want by exercising such choices than by banning things. The latter can cut both ways, as in the difficulty I have in getting unprocessed milk because of the ban on selling it otherwise than direct from the few farms of origin.