This gets you recipes and ingredients to make five meals for two people. It also works on other boxes (e.g. ones for families), but this one seems like the best value to me.
I am using this to replace my usual grocery shop for a week.
Use the code O2SUM to get 60% off the full price before the end of July, and make sure to go through Quidco to get 50% cashback. For this particular box that takes the price down to £19.60 with £7.84 cashback.
TCB also has a good cashback rate of 42 percent.