Just wanted to update this for anyone else who might search how to do this....
It works perfectly if you do as I explain above to add a simple Like & Share button that will link back to your website.

You can take it one step further if you want your site visitors to like & share individual products.

What I have done is, in my product description, I include the code
Code:
<div class="fb-like" data-href="WHATEVER_ADDRESS_THE_PAGE_IS" data-width="450" data-layout="standard" data-action="like" data-show-faces="false" data-share="true"></div>
where I'd like the Like and Share buttons to show up.
Then I add the product to my catalog and go and view it, making sure to select the url from index onwards, then go back to that product description and add the url in the "WHATEVER_ADDRESS_THE_PAGE_IS" section. Make sure to save this out.
Now when someone clicks on Share, that product, not just your website, will be shared on their Facebook, giving your products individual exposure. It's a bit of extra work, but for someone like me who creates a wide range of different items it's worth it.