My presumption so far was that all the other houses have septic tanks. OP says his site is small- so he would not have room for a septic tank system as the neighbours.When there was full planning on your site where on application did it state how you were to connect to services.? This would have to have been submitted with planning application.
Also why are you not seeking to connect to services at connection junction to current last house on laneway. In other words the house nearest your site.. Why would you need to feed from the start of the laneway?
It would indeed make no sense to dig up all the road for a completely new sewer connection if the other houses already have those connections.