I had such issues trying to convince the job centre that I could study, this was part time, but not work. So much so that I ended up finding a part time job which paid more than the ESA anyway. This was about 6 years ago, and things have changed since then, but they will quite possibly see it as; if you can study full time, then why can't you at least work part time rather than be supported by ESA. Good luck though...