Users will judge websites as beautiful or not within 1/50th to 1/20th of a second. When you are offering your services to someone who has reached the point of contacting a therapist there are still several hurdles to overcome if they are to pick up the phone to you.
There are likely at least two things prospective clients look for. Something that is both confidence inspiring and welcoming.
On the web, there are subliminal things people derive confidence from. These would include simplicity, beauty, good usability but also more technical aspects such as the speed of a site.