I was a student there in upper primary, 1964-66... The school still seems to be there, if you look on Google Maps (search for "elbinger strasse wolfenbuttel" and you should land at a marker just south of the school) - I wonder if it's still being used. It's not a British Forces school any longer, as I thing it's been about 15 years since the British Army left Wolfenbüttel.
I recall that the senior primary class, sometime during 1965, was moved off campus, I think to a part of the Barracks. I don't recall the details. The class teacher at this time was Mr Riggs, whose son Clyde was also a student in the class.
Anyway, if anyone else has memories of this school or further information, please post!