Finally some feedback from smashwords on what hoops I have to leap through to get into the commercial market, it is partly a matter of trailing paragraph spaces (they don't like them if you have an initial indent). That is easily fixed.
The other "problem" is the infamous "paragraph 7a" issue of incompatible headers. I am going to have to wrap a towel around my head for that one.
But we will get there, honest.
Meanwhile, I am having some further thoughts about what comes next. I will let you know when I know myself.