A report of pests in a building can mean one sighting in a hallway, repeated evidence in several flats or damage in a storage area used by different people. Those situations should not be treated as interchangeable. For an enquiry in Hillingdon, explain the extent of what you personally know and distinguish it from reports passed on by others. Photographs and dates give the discussion something concrete to work with. If you are arranging the visit for somebody else, check whether the occupier can describe the signs and grant access to the relevant rooms.
The inspection scope should follow those details. A technician may need access to a service cupboard, but a locked communal plant room or another tenant's premises requires the appropriate permission. Make these limits clear before the appointment instead of assuming every part of the building is included. Where access is missing, ask how that affects the assessment and whether a later inspection could be required. This avoids mistaking a treatment within one unit for a conclusion about the whole building, and helps the person responsible for maintenance understand what remains unresolved.
Once findings are available, the plan should connect each proposed action with a reason. Treatment may address the active pest while a repair deals with an identified opening; monitoring may be needed where the evidence is inconclusive. Ask how progress will be reviewed and what should prompt you to make contact before any planned return. You do not need to interpret every mark yourself. A consistent record of fresh sightings, together with compliance with the preparation and aftercare instructions, is more helpful than frequently changing traps, cleaning products or furniture positions.