Peter, can I suggest a little research? The following books may help you reach a totally different conclusion regarding the use of henge monuments.
The Stone Circles of ..... etc - Aubrey Burl
Henge Monuments of the British Isles - Jan Harding
The Significance of Monuments - Richard Bradley
Seahenge - Francis Pryor
...........................and just about anyone else in the late 20th century who has excavated and written about henges.