Woocommerce website cart tweak - need to add fractional quantities

Developed a website www.artificialgrassstore.co.uk where I want to add 'non-integer' cart quantities. eg 20.5, 10.1 etc etc. The grass product is sold in roll form and the woocommerce plugin only allows integers. I want a woocommerce/php expert to enable the checkout quantity as a box that can enter any figure.
Have a look at http://www.artificialgrassstore.co.uk/shop/classic-artificial-grass/

There are some mentions of this solution https://github.com/woothemes/woocommerce/issues/1113