To be honest I hated PAT testing and for me I would never had quoted for a PAT job as such, it was just something I would do for a customer if they wanted some done.
Saying that there are companies that do PAT alone, but I believe that it is so competitive that you are working for pennies rather than pounds.
As for the course, well IMO any training is good, wether you can convince yourself spending the money is worth it only you can answer that. If your going down the employed route, and it is a big organisation then another string to your bow is always an advantage.