Your main criteria listed is "distance" as in distance to main roads, etc. So that is the attribute you need in your network dataset. The rest can depend on the types of vehicles you need to use and road restrictions to support that set of vehicles.
"Optimal location" is a methodology and Location-Allocation can be one part of that methodology. You need to come up with candidate locations that satisfy your "distance" criteria and locations that are available to support a tea processing plant(s). And then you need the locations from where the tea is coming from, i.e., demand locations. The actual Location-Allocation process only minimizes weighted-distance between the demand and chosen facilities to give you the optimal location. So you may need to evaluate the results in terms of your overall goals and run location-allocation with different scenarios to find a set of locations that satisfy your goal.
If you do not have a network dataset, then you could use the online services on arcgis.com to do Location-Allocation or use the ready to use services within ArcMap or ArcGIS Pro.
Jay Sandhu
