Was just in tesco express (the tiny ones) and saw corona extra 4 pack for £3.11.
Went onto tesco.com and saw that this is £2.99 online, plus delivery (whatever that is).
Hope this helps, and wish I had seen this sooner as we bought 2 packs from sainsburys for £7 :(
dont forget to factor in the cost of limes at 10p ;)
website states ending 29/1
first posting, hope it helps someone.