It definitely is a beautiful picture! Using 14 count fabric, which is a good fabric to start with, the finished size of the design area would be 18" x 20". Most stitchers recommend you have at least a 3" border on all sides of your fabric so that you will have extra fabric for framing (if that's what you want to do when you finish). Thus, an extra 3" on both the left and right borders would be 6 total inches added to your width. And an extra 3" on both the top and bottom borders would be 6 total inches added to your height. So you would need a 24" by 26" cut of fabric to fully accommodate this project.
All that being said, if you're up for it, you could definitely try it, but since you are a beginner, I, and others who will reply to your question, would suggest that you start with a smaller pattern just to get your feet wet. This type of pattern is large and detailed and will have lots of colors and color changes. Even some experienced stitchers do not like bothering that kind of detail. But there are a lot of people who do. I personally enjoy them. Regardless, as you grow in your stitching, you will come to decide what you like or what you don't like.
Also, I know there's a stitcher on this chat that has been working on this exact pattern, and I'm sure she will have recommendations for you regarding it. So be on the lookout. :)