Bring books you don’t want any more, and take away books that other people don’t want any more. It's fine to take books without bringing any, and it's fine to bring books without taking any. It's also fine to take books in order to dispose of them in some other way, e.g. the 56a Infoshop. I will be Freecycling any leftovers.
There will be food; it will be buffet-style, enough to be your dinner, and it will be available throughout the evening. Vegans will be catered for by default, and other dietary restrictions on request.