I recently found out about the Leeds University Calligraphy Society, a university society aimed at introducing people to calligraphy—with a particular emphasis on Arabic calligraphy. The society holds calligraphy classes at the University of Leeds every Wednesday evening. They have lessons in Thuluth for beginners and intermediate students. Here is a link to class details: http://leedscalligraphy.blogspot.com/search/label/Lesson%20Details.
If you know of a class or course in Arabic script calligraphy near you, please send me an e-mail! I’ve published a list of the classes that I know about here: http://calligraphyqalam.com/resources/classes-and-teachers.html.