Starting the book. Sentry: By C F Williams

This is probably sounding like someone's teenage diary by now, but don't worry: we're getting to the good stuff soon.  Right now I'm catching up on the previous year, dealing with when and how I wrote Sentry.  You'll notice that all these posts are dated very close together.  That will change when we hit the present.  So then; I work full-time, and have very little free time to write a book.  Therefore I wrote it when I would be least disturbed.  Between the hours of 9pm and 3am, for three whole weeks, I wrote just shy of 130,000 words.  I attribute that to being an ex-IT professional, whose only outlet for social interaction was the keyboard.  It was what most doctors would probably refer to as a "manic episode", but I just had to get the story out.  I'm not a "finisher", as defined by certain online tests you can fill in about your personality-type, so I knew I had to write Sentry now or never.  If I even paused for a day or two, everything would stop.  I know I am writing about the past, but this has played out for the sequel and other books I have intended to write at leisure since, but I have never finished a single book.  The only fortunate thing is that it is only a year since my first book was written, so I have time...for now.
Anyway, this post is about how I wrote Sentry:
I did not have a plan.  I did not have a plot.  I did not have "Character Sheets" (look them up online:
http://www.epiguide.com/ep101/writing/charchart.html, for example - apparently you have to have them); I only had an idea.
The idea was that a form of life could exist in a very simple structure, like a set of transistors, culminating in a Flip-Flop (the fundamental elements of any computer http://en.wikipedia.org/wiki/Flip-flop_(electronics)).
A simple set of atoms that could combine to hold a minute fragment of data.  That was it.
From there, I thought it would be great if that life form inhabited an entire planet.  Then I wondered what would happen if someone got hold of such a planet which could calculate the most complex equations at will, given the correct stimulus.
Then Sentry was born.  http://www.amazon.co.uk/Sentry-ebook/dp/B00EN4J95G
And that was it again.
So, I wrote the book from chapter to chapter, not knowing what the end would be until it came.  I have to say that at 80,000 words (an approximate minimum length of a novel
http://storytime.booklamp.org/2012/03/19/how-long-is-the-average-book-a-concrete-answer-to-a-longstanding-writing-faq/), I was a bit disappointed that I still had some work to do, but the story was the story, and it had to be finished.

Right: so that's the boring stuff out of the way!  Now let's get to the good stuff - how the hell am I going to sell this thing!?  It's seat-of-the-pants time, as you discover, along with me, what works and what doesn't!