Start with the equipment, not a shopping list of sockets. Lighting, a laptop and occasional tools are a different electrical brief from continuous heating or workshop machinery.
Describe the full load and route
Tell the installer what will run together, where equipment will sit and how the cable could reach the building. Include outdoor conditions, future access and data needs.
Use a competent electrician
Electrical work must be designed and installed safely and may fall within building regulations requirements. Do not treat an extension lead across the garden as a permanent supply.
This page will be expanded with current official electrical-safety sources before launch. Until then, use it as a briefing checklist rather than installation instructions.