Sell by, Use by, Best Before dates should be taken with a pinch of salt. They are always tend to err on the safe side. Seriously something dated use by end of October doesn't suddenly go off at 00:00:01 on the 1st of November.
I've eaten plenty of cans/packets of stuff dated weeks or months after the use by date.
Of course with fresh foods you have to be more careful but you can generally smell when a chicken fillet is off, milk is off etc...