The problems of being on a zero-hour contract are manifold. There is no job security from year to year and you are unable to plan ahead because you never know how much you will be earning in the future.
In my own case, I find it difficult to arrange childcare because of the variability of the hours on offer. Moreover, I have been expected to go to meetings that I am only partially paid for or sometimes I get nothing at all. I attended a meeting recently and my manager was most disapproving because I walked out at the time I had been paid up to.
I work in FE and you are only paid for contact time with the students so all preparation has to be done in your own time. No holidays are paid for so you have some months when you get no wage at all. If the departmental budget is all spent before the end of the academic year then you are told that you have to finish working early; even if a later ending date was agreed in the previous September.
The consequence of this treatment is that you feel under-valued as an employee. Full-time staff do exactly the same job but they are paid for doing preparation and for their holidays.
Zero-hour workers are exploited and vulnerable because no one dares to say too much to management for fear of not getting any hours. Also, the staff who ingratiate themselves with the management are often seen to get the pick of the part-time hours.
The fact is a zero-hour contract is not there to provide an employee with flexibility but to provide an employer with a cheap labour force!