How far out of date?
If it's tetra packed, undamaged and not hugely out of date, I'd use it. That said, is it worth the hassle for the sake of 80p?
I drank severely out of date orange juice (i.e. about 5/6 years).... I bought it as a student, then forgot about it until it got mixed back in with general supply during a house move. It was like eating a chewy yoghurt ball floating in a carton of urine. I now pour juice into a glass as a matter of precaution.