Chelmsford police station is 14.3 road miles.
Colchester police station is 13.1 road miles.
However Colchester police station is 11.4 straight miles away while Chelmsford police station is only 11.16 straight miles away.
So technically Chelmsford is closer.
Jeremy had no way of knowing this because internet maps with route planners did not exist. The idea of calling Chelmsford and not Colchester being incriminating is rather baseless as Jeremy couldn't have known the precise distance between the two.
According to Bews and West, Jeremy tried calling Witham. Tiptree police station was only open part time.