I found this solution:
Override loop template and show quantities next to add to cart buttons.
It worked for simple products but not for variable products - the variables still show up without quantity options.
Note that I pasted the code into add-to-cart.php replacing all the existing code. I backed up the original first!
I found add-tocart.php in plugins/woocommerce/templates/loops/
After doing the above I was able to reinsert the short code for add to cart... and the result was that quantities showed next to theadd-to-cart button!