Marks and Spencer have a wine sale- save 25% when you buy 6 bottles.
If you are buying a '£10 Dine In', the wine in that counts as 1 so you'd only have to buy 5 more to get the discount.
Although the offer states champagne and spirits aren't included, they are when put through the till.
Online, there is also 25% off all cases of wine.
Not sure if this offer will be repeated before Xmas, so might be worth stocking up.