Need help using product model data in cart

Hi, I'm trying to use the stock_status field from model/product/product.php in view checkout/cart.tpl - it seems that other fields are already being used from the product model in this file, but when I try to reference $product['stock_status']; it throws an undefined index error.

I've looked at the information on here about the MCV architecture and understand the structure, I just don't know what I'm supposed to do to make this field available in the cart. I've also looked at a number of posts about users adding brand new fields, and I've tried to follow along as best I could given that I'm using different files, but still no luck.

Any help is greatly appreciated.

Thanks :-)