Tristan,

The idea I had earlier was a way of doing this but it does rely on small numbers of large purchases to be worth the effort. the basics of the idea is that if you donate money to a charity they can claim somthing called gift aid which is basically the government paying back the income tax you have paid (donations to registered charities are tax deductable).

My idea is to give the money to a charity on the proviso that they will then spend the money on the relevant item burgers / beef in gravy and use you clubcard. This means that they then get the gift aid back fromt he government and as they have purchased the food there is no legal or health and safety issue in them using it.

It's a win - win as far as I can see. The only thing I have yet to do is to find a charity that can do this. If I do i will of course post on here.