Can you call her, or someone in the guild & find out what size they want the block to be when you're done? There are a lot of non-paper pieced house blocks out there. You could probably use the fabric provided as the back ground, as most of the block would be from different fabrics. Many are 12", but you could use the fabric provided to enlarge it, like sashing.
http://quilting.about.com/od/quiltpa...ck-Pattern.htm