I have received a few emails recently about this, asking for advice on how to go about teaching languages in Primary Schools. I must stress here that I only have my own experiences to talk about and that there are many other ways to go about this.
I have not retrained to teach Primary, but I have modified my methodology - a lot of imagination is needed and a love of singing and story telling!
I have set myself up as a business. This means that I do all of my marketing, finance and admin myself, as well as the actual job of teaching. In the first instance that means writing to schools, advertising in directories and magazines and spreading the word. Then comes the hard work of making sure you deliver the service required and keeping up the momentum, as well as making sure that your accounts are up to date and that you have adequate insurance.
PMFL on its own would not be feasible, in my opinion. If you do want to go down this route, then you must be flexible and offer a range of services, otherwise the business is not financially viable.