Luckily, "The Book" isn't an issue in the UK - there is no set text that people all use. Songbooks tend to be personal notebooks or files where people complie or write out their own versions of the songs.

I'll add my support to those who say by all means use a cue-card or a few notes that you can have handy if necessary, but don't sing FROM the book. I don't like it when a singer stands holding a book as if they were singing in church, reading every word, including repeats and choruses. That's just lazy, and almost never leads to a good delivery of the song. On the other hand, having a few notes (beginning of lines/verses; tricky words like place-names that you keep forgetting, etc) could get you out of trouble. You may not have to look at it, just keep it handy. And the act of creating those notes - asking yourself "Which bits do I know, and which do I tend to forget?" actually helps you learn the song, and perhaps realise that you do actually know big chunks of it.

Marje