Visit the place a few times before you join. Note the layout and atmosphere. Look for steps or ramps. If you have vision problems, check the lighting. Check the temperature.
Excessive heat can cause multiple sclerosis to flare up.
Irregular temperatures may be hard to take if you have a neurological disorder. Note the air quality if you have a lung condition. Ask if there are trainers familiar with your disability. Tell class instructors that you may have to adapt their routines to your abilities. Trainers may be afraid that you'll get hurt while exercising.