You do not need measurements of every gutter to begin. Say which sides of the home need attention, whether smaller roofs have separate gutters and where water escapes. Include the postcode and photographs taken from safe ground. If a section cannot be seen, identify that uncertainty instead of guessing its length or condition.
For Orpington, describe the route to the rear and any locked passage or shared entrance. A straightforward account of the requested cleaning helps distinguish a main-roof clearance from a job that also includes a porch, conservatory, downpipes or exterior boards.