You will need to demonstrate that all operatives working on the project are deemed competent to carry out the works. Training will therefore be required if not already in place. This includes subcontractors; you must be satisfied that they are competent and equipped to carry out the works safely.
Having some form of site management health and safety qualification is a legal requirement.
Ideally, an SMSTS trained Site Manager will need to be on site at all times. Therefore, it is advisable to have 2 persons trained in case one is indisposed for any reason.
A fully qualified first aider is required to be on site at all times.
A fire marshall is required to be on site at all times.
Additionally, you will need to comply with all other relevant regulations, such as the Work at Height Regulations, Control of Asbestos Regulations, COSHH Regulations and many more.