Thank you very much for clarifying. There are a few options for you:
One is to have a zero hours contract which means that you simply do not guarantee him any minimum hours of work and he cannot have an expectation of any hours from you. The drawback is that any hours offered to him, he is free to reject and there is also no obligation to accept them. He may never exercise that right but it is important to bear it in mind.
You could have a normal contract, with set hours, but also have a lay off or short time working clause in it. The formal definitions of these two options are as follows:
- Lay off - if an employee has been told to go home, unpaid, for at least one full working day.
- Short-time working - if an employee's pay for the week is less than half a normal week's pay.
You can therefore rely on that clause to shorten his work or completely remove him from duties, if business dries up. The drawback there is that it has a limited shelf-life and after 6 weeks he can start a formal request to be made redundant instead.
Finally, you can still have a normal contract with set hours, but a clause which allows you to make changes to it as and when necessary. The drawback there is that such a clause does not give you a free path to make whatever changes you want, you would still need to give him reasonable notice and, if challenged, you have to be able to justify why such changes were necessary in the first place.