Is there a way to set a fixed width for the characters in HTML?
What you're asking for is called a fixed-width font. As James Hopkin remarked, HTML text in <tt> or <pre> tags is rendered with a fixed-width font. 
However, what you describe sounds like a table. HTML has direct support for that, with <table>, <tr> (row) and <td> (data/cell). Don't bother with fixed-width fonts; just put your A and the Z in the second <td> of their rows.
Is there a way to set a fix size for the characters in HTML?
That means, say …
First row, 8th character is “Z”
Second row’s 8th character is “A”
I want to print out , when printed the “Z” has to be exactly on top of “A”
*Note: I'm using the insertHtml method in QTextEdit()