Bring books you don't want! And adopt books that other people have brought.
I'll do food — will be buffet-style, enough to be your dinner, and available from the start of the evening. Vegans will be catered for by default; let me know if you have some other dietary restriction that I need to take into account.
I'm happy for people to come at the start and stay till the end; or to just pop in briefly to drop off some books; or anything in between.