You would be correct in your assumption. The course is a basic introduction to entry level aerobatics and should leave you with sufficient knowledge and technique to perfom basic level aeroabatics solo in a suitable aircraft.
As you undoubtedly know there is no legal basis for the course in the UK because a rating is not required to fly aerobatics but you would be reasonably silly to teach yourself so the course provides a very good way of obtaining the necessary skills. There are other ways to go about it such as flying with a another pilot who is current in aerobatics, but he may not have the same ability to teach.
In my experience some pilots take to aerobatics and others never do. I think you need to feel comforatble performing aerobatics solo and have sufficient self belief that you can and will recover from any situation that doesnt go entirely according to plan. I really believe that some pilots will always doubt their ability to recover from a spin for example and will never as a result be comfortable with aeros even though they have been through the AOPA course.