My local Tesco Extra has all the 6 packs of coke 330ml cans at £1.42. I found regular and diet varieties next to the other pack sizes.
I think this size pack must be discontinued as they are no longer listed on the Tesco website. 8 packs seem to be the new 6 packs!
Even with all the different offers on various pack sizes this is still the cheapest per can.
8 pack £3.50 43.8p per can
or 2 for £6 37.5p per can
12 pack £4.39 36.5p per can
or 2 for £6.50 27p per can
24 pack £8.25 34.4p per can
6 pack £1.42 23.7p per can
All per can prices approximate for comparison purposes - please feel free to correct my maths