Any work voluntary or otherwise with people with disabilities will provide you with a good knowledge of what this work is about. The more you do the more you will be comfortable with communicating and working this great group of people.
There are a lot of voluntary groups around which are open to anyone interested in the area to come and help and this will expose you to the various levels of need and the different age ranges and therefore the different levels of support services provided within this sector of care-work.