All my ideas are rubbish!

Ideas are greatly overrated. Execution trumps premise every time.

See also, Watt-Evans' Law of Literary Creation: There is no idea so stupid or hackneyed that a sufficiently-talented writer can't get a good story out of it.

It also sounds like you struggle with the mid-book.

Don't worry about this. Everyone struggles with the mid-book. Just bull your way through.

www.shmoop.com has detailed study guides of hundreds of novels. "Reading" a book at this level primes me to think at that same level while working on my (imaginary) novel. Maybe it'll do the same for you?

I have similar issues myself, LadyA. I hardly finish what I start, and my attention span for writing is the equivalent of a fly. Freewriting and outlining have had no effect on me. Sometimes, I wander through the day in what I call a "writer's funk."