You'd think it would be easy - Help needed!

http://issuu.com/whitstableimp/docs/whit_may2010 - see interview pages 14-15

After a while, book promotion takes on a momentum of its own. I just received an invitation to organise a CURZON PANEL for Havant Festival in October 2010 - more of this later. It's lovely to receive invitations, but I don't want to be like the "gal who can't say no" and have reluctantly turned down a couple of requests for talks during National Crime Fiction Week (14th-19th June). I'm already giving two talks after work that week, at Ruislip Manor Library on Tuesday 15th and Ickenham Library on Wednesday 16th, as well as my normal weekend bookshop events.
My second book, ROAD CLOSED, hits the shelves in a couple of months and I've just received a proof copy in the post! I'm so excited! (I think my publisher rushed it out for London International Book Fair, before the International part disappeared in a puff of ash.) There's something surreal about opening a book and reading your own story on the pages. ROAD CLOSED has already been selling well with preorders on amazon, which I'm absolutely thrilled about as I'm assuming these can only be readers who enjoyed CUT SHORT so much they're looking forward to ROAD CLOSED. So far so good.
I'm now busy writing (of course!) and am around 3/4 of the way through the first draft of DEAD END, the third in my series. I want check it, and research the fourth book in the series, over the summer.
When it comes to writing, creating a ficitious reality in words comes easily to me - I absolutely love doing it. The words just roll off the keyboard. Sometimes when I'm trying to get to sleep, an entire chapter unfolds in my head and I have to jump up and jot it down. Where I struggle is with the organisation (shudder). When I wrote CUT SHORT, it's no secret that I didn't plan. I just sat and wrote, for fun, for myself, with no idea anyone else would ever read my MS, let alone publish it. When I had to knock it into shape as a coherent book I got into a terrible muddle.
With ROAD CLOSED I was determined to make the process flow more smoothly and devised a detailed plan on a sheet of A3, writing down what each character was doing on each day through the investigation. Couldn't go wrong? Well, everything was going fine until I had to move a few chapters around. Muddle and mayhem, some tearing of hair and a few choice expletives, but I sorted it out in the end.
So, twice bitten... I wrote a 9 page detailed synopsis for DEAD END before I even started writing the MS...
... and here I am, 3/4 of the way through, and I've just shifted a chapter. This means about ten other chapters have to be moved around, and others reworked. Muddle and panic again.
Why not leave well alone, you might ask. My books (as I hope you know...) create authentic realism shot through with drama. If the day to day realism goes on for too long, it becomes dull. Who wants to read about boring the daily life of a police investigation? On the other hand, too much drama and terror in one section loses its impact. I'm very keen to make my books terrifying without becoming implausible. If my readers can really believe in the world I create, I think that's more frightening than if I pile on the horrors. There's no right or wrong about this. It's just my opinion. So the balance between realism and drama is crucial.
I was happily writing DEAD END and my agent suggested there was too long a patch of investigation, and then two hugely tense scenes built up at once. Of course I saw the sense in what he said. I would have reached the same conclusion myself when I come to review the whole shape of the book once the first draft is completed.
So I'm shifting chapters around again... with all the consequent changes. I can't have a character reminiscing about a scene before it's happened... or a Saturday night party taking place between Wednesday and Thursday... oh heck! I wish I was more organised!
The MS isn't due to be delivered until after the summer for publication in 2011, so there's no rush, but there are so many demands on my time. I don't have the luxury of being able to devote myself full-time to writing, and will be back at school tomorrow. And then there's the book promotion to fit in ...
Do other authors plan their books successfully before writing? And if so, HOW?