As Duncan mentions in his majestic thread, they currently have a bin end sale going. Varies from store to store and once it's gone it's gone

Asda also have a limited bin end sale on their online wine store not much to shout about IMHO, possibly worth looking at the Albariño on sale for £7 but not much else would take my fancy. There are also other wines on offer on the site so worth a look

Tesco has a selection of wines on offer as part of their wine festival. They are also offering 15% off when you buy two cases of any of their fine wine range (Max 2 cases IIRC)

M&S are also running 25% off 6 in store or 2x cases of 6 online. I believe this runs to 5th Oct