My esa stops in March but still not fit what can I claim?

I was on a 12 month agreement for ESA but when it was due to stop but when I rang them up they moved me into the support group that means I was able to carry on working without it effecting me. You will be limited to the amount you can earn and the number of hours you work. For me it takes me longer to do stuff so I will work for free (volunteer) for any hours that are over my allowed time which I think is 15 hours a week.