I faced the same challenge three years back. I had the same profile of students with the age group varying between 15 and 65 years. One vital point you need to keep in mind is the fact that since none of the students are educated they will be very open minded and will not carry any pre conceived notions. They will diligently follow your instructions.

The first thing you need to do as a trainer is to instill the confidence that neither age nor education is a barrier in the learning process. We keep on learning till the last breath of our life. Scondly you also need to tell them that grammatical accuracy is not required for speaking the language. Just like they mastered their mother tongue, they can grasp the English Language also. You should be an inspirational force for them to get motivated and challenged to pick up the language.

Keep the usage of mother tongue to the bare minimum. Treat the whole group as one unit and make yourself part of the group. Create an informal atmosphere wherein no one feels shy and everyone opens out. It will unarguably require lot of patience and commitment at your end.

From my personal experience, let me tell you that when you ultimately bring them to a level where they can speak the language, the satisfaction and pride of having turned around a group of this profile will take you on a different plane.