Here are a few more random thoughts about the difficulties you might face with this project.
Remember, they are adults; they can vote with their feet. Right in the middle of a session they can get all flustered and decide they've had enough for that day. Let them go. Smile, wish them a good evening, and say they will be welcome the next time they come... You hope to see them soon. Leave it at that.
There are many useful worksheets on the internet, but, they may be more use to you, than the learner. The learner is usually happy to work very hard, for a small amount of progress. It is much more important that they work at the pace they can manage, than that you cover all the ground you prepared.
It's not about 'fun' either, although every session should contain a game if possible. More use, is a three-dimensional aspect to your presentation... something that can be touched, passed round, manipulated.... something that can be mastered with a little practice.
Sometimes there is a genuine difficulty in wielding a writing tool. Get these learners on to a keyboard if possible and encourage them slowly to learn touch typing, after they have played with the alphabet till they are really comfortable with it, and also, comfortable with a dictionary.
There is also a group who have good short term memory, who seem to be picking things up beautifully, but, when you test their versatility, they have not really understood what they seem to have learned, and soon forget it again, between sessions.
Another thing to bear in mind, is that the appearance of a classroom may be enough to put such people off. Some are phobic about holding a pencil, or hearing chalk on a blackboard.
Quite often, those who simply never had an opportunity, and especially if they are now Christians, will learn quite quickly, (compared with some others), but, [i]wanting[/i] to learn and to change, is essential. You can't do that for them.
A lot of love may be needed, but, there is a saying which has been developed by teachers of dyslexics, which is, that [b]if the learner is not 'learning'[/b], :-? then [u]the teacher has to change the way they teach[/u], 8-) until they find [b]the best way for the [i]learner[/i] to learn[/b]. ;-)