Regulation A1 lists freestanding walls (including steel ones) and wire fences up to 1.8 m as minor building work. A steel palisade fence is not named, so it is the building control officer's call; councils usually treat one up to 1.8 m as minor work, which means you apply but plans can be waived. A wire fence needs neither plans nor an application. Above 1.8 m, it needs plans and possibly a zoning relaxation.
A gate or gate motor is not normally a plans question, but a gate may not open over the pavement or council land without permission, and electric fences need their own electrical certificate.
Sources
Checked October 2026. Councils change their tariffs every July, so confirm fees before you pay.