Is it possible for the drawspace to just make a pdf "book" of all the lessons....

It may be possible to do so, but probably unlikely.

People here are at all levels of expertise and like to pick and choose their lessons according to ability. Having a full 'book' of them would make it more cumbersome for them to find lessons.

From a technical point of view, a full book of lessons would be HUGE to download

What some people do is print off the lessons then put them together in a folder so they can refer to them. Alternatively, you can purchase one of Brenda's books on drawing which may be what you need.