The short answer is yes, and in effect you could sign off the installation yourself. However do you have liability insurance? If someone dies or you have a fire the blame will rest on your shoulders.
If you are confident about your installation abilities, and its a have the time but not the money situation. I would get the 'on site' guide. Brush up on your installation requirements, plan and record all your design details and calculations and get someone else to inspect/verify it for you and give you the certificate of completion.
After all besides installation requirements it is a matter of four important figures, prospective fault current, earth loop impedance, RCD response time and insulation resistance.
Also, when you come to selling the property you could be required to provide the test certificate for the job. Good place to get your accessories from though is
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