Permitted work and ESA Medical

Hi I've my ESA medical next week and it's booked for straight after work. I work 12.5 hrs a week and just about manage to keep this together when I'm unwell. I have bipolar but am ill 8+ months of the year. I'm well atm as have just come out of an episode. Will I be penalised for looking like I've been at work, and being honest about this. I'm a support worker for vulnerable young people. My work know I'm bipolar and accommodate this in the duties I'm asked to do. In my last episode I got sent home sick as I couldn't stop crying and took time off as I wasn't coping. Should I be honest or should I change my clothes and not wash my hair and not mention work and look like their stereotype??? I know damn well I couldn't work full time and that I would get sick and not hold it down. What I have atm works and I'm really doing my best!