You would have to create 2 kinds of manual shipping methods. One kind with post code ranges to handle the shipping of all the products. And one other kind with post code ranges to handle the shipping of only the products which aren't limited to an area.
Depending on your rules and post code format, you might end up with a lot of manual shipping methods. So it might not be practical to go that road. In that case, a custom shipping plugin would indeed be preferable but would require to have a developer to work on it.