You could try this in your SQL:
SELECT LEFT(code & ' ', 11) as code, description FROM myFile
It concats eleven spaces to the end of the code, then grabs the first eleven characters of that string. So basically It's a pad right.
---- Added ----
For this to work, you'll need to set the font on your combo box to a
monospaced font[
^] like Courier New. Here is a
list[
^] of others.