How do I add alphabetical lettering in the left hand margin at every fifth line, the first letter “A” being placed against the first line in each page?



It should look something like this:
http://imgur.com/4V4cEft

Within the first column of the table there will be text.

Try putting the letters in a borderless text box and put that textbox in either the header or footer. See the Letterhead Textboxes and Styles Tutorial for an example of how this works.