Just got back from Tesco where they are selling a selection of £4.99 wines @ 3 for £10. Furthermore, if you buy 6 bottles you get an additional 5% off the full price i.e. £1.50 - making it 6 bottles for £18.50, or in other words £3.08 a bottle instead of £4.99.
I'm not sure of all the wines they have available but I bought Lindeman's Chardonnay; Big Kahuna White and Pont D'Or Grenache Marsanne.
Can't seem to find the offer online, although there are some pretty good offers (especially the 50% off) which is the link I've provided. Vouchers are for online purchases.