After much soul searching I've decided not to do the course. Despite support from GP and tutor who know my limitations and struggles but who wanted me to feel like I was doing something, we've all come to the conclusion that the DWP might not interpret it in that way. My ESA50 form did not say anything that I could not support/prove, for example under the dexterity I did put 'it varies' but my health is very variable hour to hour etc. Plus I did not think I could live with the stress of doing anything 'wrong'.
Thank you all once again. Not the decision I wanted to make, but I know now that it is the right one.