The determination of your hours of Work Preparation is not an exact science and is at the discretion of your Work Coach. There are currently 25,000 Work Coaches in the DWP so there could potentially be thousands of different views about your Work Preparation. A lot depends on human nature and the empathy or not with your Work Coach. If you find that the relationship with your Work Coach is non-existent you can send a UC Journal message requesting a change of Work Coach which in my experience is usually allowed and it is best not to be critical of your current Work Coach as the Jobcentre staff may become defensive.
Let me know how you get on. David
Nothing on this board constitutes legal advice - always consult a professional about specific problems