From tomorrow, 6 packs of McCoys crisps will be on offer for £1 per multi-pack. However, Tesco currently have a code for 50p off any 6 pack, valid until 10th August - combine both deals and get a 6 pack for only 50p!
50p off when you buy any McCoy's crisps 6 pack
I'm unsure if an equivalent voucher is available in store (HUKDers?) but I've just placed an online order and it worked :)