There are at least two things to avoid buying after the use by dates; bagged produce and liquid dairy products. If milk doesn’t have at least a week left on the use by date, I won’t buy it. Bagged produce must have at least three additional days. Bread it kind of iffy, unless you are making something that works better with bread a bit dried out, like French toast.
Most other items are just fine for quite a while.
This morning I used the last of a gallon of milk in my coffee. The “Best Before” date on it is September 16.
There was NOTHING wrong with the milk.
My GF tosses anything dairy out 3 days BEFORE the BB date. Even parmesan cheese!
Keep it COLD and it’ll last well beyond its BB date.
The same goes for just about any foodstuff. Meat being the exception. I feed week overdue meat to the dogs, but eat everything else up to that point.