You could try looking at these sites to see who has the most coverage: This site usess the old Sitefinder data but bare in mind it's from 2012 https://fusiontables.google.com/DataSou ... J#map:id=3
While here they claim to be up to date but noticed some sites don't appear. https://www.mastdata.com/37/37_map_mobi ... tford&Z=14
Though you may have to zoom in quite a bit before the sites placement marker appears.
But to give you some idea. Vodafone has a mast at Tree Heritage, Orange Bramfield Ln & Warrenwood Ind. Est, Three Warrenwood Ind. Est
all three site share to the right of the A602 before Mill Lane