A little late in replying, I have been on other projects, but I have figured this out now...

The files to change is:-
includes/modules/product_listing.php

(of course, dont modify this file, but put a copy in the sub directory named after the template, i.e. includes/modules/Nanzza/product_listing.php)

I changed the Select statements on Lines 15 and 21 to include pd.products_description.

Then on line 54 I changed the 'text' variable to add in the extra information I need, i.e. Product Description and a More Info button.

Laurie