I am really enjoying mulling this idea around in my brain, and it's great because nothing is fixed yet (well, not really), and so I can alter plot and characters and philosophy at whim, and it is all now starting to swirl into something that I think, when it's finished, will be very cool indeed.
I have also completed the prologue and the first three chapters of Inter Vivos. I may, of course, need to revise them when the whole novel is written, but for now, they are pretty much as good as I can get them. I have also (drum roll ready) worked out how Inter Vivos is going to end. This is extremely exciting, because now I have something to aim for, rather than just writing randomly to see where it leads (which in my case was nowhere fast).
It's all coming together, and although there's still a long way to go, I feel a lot better about everything now.
I am currently re-reading Harry Potter and The Deathly Hallows, and have made the monumental decision not to begin re-reading the HP books again straight afterwards (yes, I am feeling ok, thanks for your concern!). Instead I am going to read one of the several new books I received/bought myself over Christmas. Only problem is trying to decide which one to read first...