Busbar.
In response to your question about the interview courses. I attended both a few years ago, and whilst they were okay, neither IMHO will give you a significant benefit preparing for the BA assessment. If I had to choose one, it would be Penny's as this was on a one to one basis.
If you search this thread there is some really good info. You can buy the software to practice for the computer based tests, and books to practice verbal & numerical reasoning. The interview questions, apart from "tell us about yourself" are based on demonstrative competencies, ie "give us an example of when you played your part in a team/made a good decision/dealt with conflict", you get the idea.
Hope this is of some use.
But whatever you decide, best of luck!
737 Jockey