Most (all?) of the big fabric companies have free download patterns. Start your search with Michael Miller as they may have one using fabric from the line you selected. I saw more than a few (French Post) that uses large blocks of focus fabric and looks easy to enlarge as you just continue to duplicate the pattern longer and wider.
Download the pattern, look at it and decide if it will be easy to enlarge. If so, multiply the dimensions to the new size you want then use the same equation to increase your fabric purchase - and buy extra :)
I wouldn't attempt to match colors online. Either purchase fabric from the same collection and colorway as your focus fabric or purchase the focus fabric then take it to your LQS to buy the other fabric.