I do lots of below the line stuff: brochures, leaflets, training manuals, product literature, sales letters ...

'Copy' is now ditched. It's official.

Me, I'm a Writer!!

Yes, you are ‘a writer', but I think 'Technical Writer' would be more to the point. Technical writers write all of the documents you mentioned above. Novelists (also writers), write novels; Essayists (also writers), write essays; Poets (also writers) write poetry: they're all writers, but their ‘labels’ are more informative about the kind of things they write. It really all depends on how specific and informative you want to be, and what the point is of putting a label on yourself. If the label is for others, and your intention is to be informative, then ‘Technical Writer’ is more informative. If the label is for you, then what does it really matter? You know what you are and what you do.