You can ignore Best before dates as long as the food is palatable. Use by dates are a bit more important as they are on high risk foods which are putrescible. It is illegal for a shop to sell food beyond its Use by date. I am unaware of any cases of notifiable illness i.e. laboratory confirmed infections that have been caused by eating out of date food as the organisms do not just generate in the food without it being contaminated or undercooked in the first place.