I have recently gone back to work on a 16 hour contract. It's supposed to be flexible working hours, meaning they want me to be available pretty much every hour of the week so i can fit in with their hours. I currently work several evenings a week, not my choice but it seems to have become my working pattern. Anyway i need to swop one evening for a few weeks as i have a regular hospital appointment. Line managers solution is to book it off as annual leave, for 4 hours a week. Is this normal on a 16 hour flexible shift pattern or should i just say i am unavailable those days but am willing to work other days?