A loose support, a damaged insulator and an unfamiliar energiser warning can need different repairs. Give the electrician the symptoms you have already noticed and any earlier findings. Ask what the inspection found, which corrections are needed and whether other work on the wall or gate must happen first. Keep that explanation with the quotation so you can compare the same work if another contractor is involved.
If a fence section cannot be inspected, ask what access or further attendance is needed. Keep outstanding items clear before the certificate is considered complete. For a boundary beside the reserve, arrange the relevant access separately; a public visitor booking does not provide contractor permission. For an ordinary private boundary, use the property entrance and access arrangements agreed for that installation.