The expiry dates on camera film (b&w specifically) - how important is it to stick to these? i.e can they be used after the date printed on them, or will the photos developed really look all that bad?
Just like food, the expiry date is a warning after which the supplier is no longer responsible for any defects. However in my experience foto film can last for 2 or 3 years after its Use by date.
like the previous answer, film is like food in the sense that it will go 'off'. For the price of a new film why bother taking the risk of ruining a superb picture or event?
I wouldn't worry about it.
One of my favourite photographers is Wilfred Thesiger;
http://www.prm.ox.ac.uk/thesiger.html
He spent long periods living in the Gulf in the 1930's 40's and 50's and took photographs of the pre-oil Gulf Arabs.
He kept his undeveloped, but exposed, films in a leather pouch in temperatures of 50 degrees C+ for months, if not years, and his pictures were fine.