As others have said, the downside of relying on self employed staff is that they can do pretty much as they please. As soon as you start putting requirements on them, the law will treat you as their employer anyway, with all the implications that provides. If your business really needs a well motivated busy committed member of staff (albeit part-time) that you can rely on, then quite frankly it is far better to steer clear of self employed arrangements. Your business is what matters. This person does not work for you or your business, and it really is up to them how they conduct their own business, so I'd have a complete rethink about your staffing arrangements from here on.