Continue shopping url

HI there

I am in the final throes of a design for a customer who has asked that when a customer clicks “add to cart” on single product page that offers the option of:

continue shopping and checkout

Easy right? And I have done just that except that continues shopping simply links the the top category /shop/ url.

Instead he wants it where “continue shopping” goes to the primary category of just recently added product instead of the generic shop url.

Does that make sense? I have literally gone crosseyed trying to figure this one out.

cheers so much