This is actually McCoys 6 pack but you get 3 free packs. So 9 packs for £1 making it 11p per pack is pretty good (let's face it 10p per pack days for these are unlikely to happen). :(
Sorry I don't know when the offer ends as I was in a rush. But this was the offer when I popped in earlier today.
Usually £1.50 for a 6 pack.
This offer works out to be better value than the BOGOF that was recenly in Tesco.