There is a Coppid Hall Farm in Havenstreet. It seems that the word might be Middle English and possibly means 'couped in' - another of those place names that might have been very specifically local and which may not have been formally recorded, save for in a few documents such as your will. I've got a copy of the Domesday Book at home (but I'm on holiday at the moment) - I'll see if I can find anything in there. P