I am insured through Fowler Penfold brokers, Insurers are Allianz Global Corporate & Speciality AG with the underwriters being Mercia Marine
My policy does not state how far from shore but says: Inland and coastal waters of the united kingdom, waters between Brest to the river Elbe and all passages between.
I read that to say I can go anywhere I want to go within that area including the whole of the English Channel
Martin