Always check out my local as they do have some really good deals. This should be nationwide as it states on the website.
2L Bottles that work out to the magic line of £1 per bottle.
ASDA are doing the usual 2 for £3 when I went in on the weekend. Great deal with the weather we have been having, just got 9 bottles for a hopeful BBQ this weekend ;)
Link is to a store locater for ease of use! Hope there is one near you!