Instructions:Came through to my inbox today - not sure if it's customer specific..hopefully not!
Unlike their usual 'free delivery' where you have to spend at least £40...this is no minimum spend :)
Says valid until midnight on Saturday (guessing 31st July but might want to check it wasn't yesterday and the email came through late so please post a comment if it doesn't work for you)
Don't forget Topcashback...
Hope it helps someone out :) If it works, heat and rep welcome. Ta muchly x
Extended to Monday 2nd August