I've deicided to break out of the box and just write the first bit of my book. One of the problems with plotting the start of act two, is that I just don't know how much backstory will have come out and how much my characters will have talked about their issues.
So I just said, "What the heck!", and started writing, and before I knew it I was at the end of chapter one. (Woo Hoo!). Just goes to show that every book needs it's own approach and we shouldn't feel afraid to try something new. Normally I would find it difficult to write without a clear plan, but actually since I have been sitting at my keyboard, I've actually been less worried about my black hole.