For the UK start, provide the address where you want the journey to begin and describe anything that could affect access, such as a controlled entrance, limited stopping space or a preferred alternative meeting point. A collection location and requested time are planning details to confirm for the individual enquiry, not assumptions made from “London”.
For the Netherlands end, send the exact destination and say who will be travelling onward with the pet. If the road journey is intended to finish at an airport or another meeting point rather than a street address, explain that at the outset so access and the handover can be discussed.
Dates, collection timing, crossing choice and arrival arrangements are all reviewed against the addresses and travel details you provide. Ask for the proposed plan to be confirmed before relying on a particular time or meeting place.