'I also have poems hand written by BOYD which he gave to my mother in which he states they lived at "Sea Haven". This could be a town in Sussex or the name of their house anywhere. It did in fact a sea views according to the poems.'
Have you tried to find Sea Haven in 1939, just to give you some indication of how many houses appear - though unfortunately several other houses with names seem to be mis-transcribed and do not result in a hit. Sussex does have a Sea Haven.
In addition, you could look for references to Sea Haven in the newspapers for 1945-1949, just to see what is around.