Why do you have to provide PSC details?
This new rule was introduced to try and stop the practice of nominee directors and shareholders where the ultimate ownership of the company was not transparent. This is where a person who is nothing to do with the day to day running of a company is appointed as a director or shareholder to hide who is really behind the company. This is a popular tactic for people involved in tax dodging, money laundering and fraud.
In most cases when setting up a limited company the PSCs will just be the shareholders that you are appointing. You are also required to keep a paper Register of your PSCs.