For items to work you need a live and neutral, the earth is protective and does not provide function ?
It is not
intended to be a current-carrying path under normal operating conditions. But if you connect a load between L & E, it will become one.
Take an old TN-S arrangement. You have L & N running from the transformer to the house, and the sheath of the cable is used as the protective earth. At the transformer, both the neutral
and the cable sheath are connected to earth by an electrode, i.e. the neutral and the sheath are connected together. Normally, the sheath is used as the protective earth, and will carry current back to the transformer only in the event of a fault. However, if you connect a lamp or other load between the live and the cable sheath at the house, it will light, since as far as the electrons are concerned the sheath is just another metallic path back to the source of the power.
With TN-C-S, you don't have a separate metallic path all the way back to the transformer, as N & E are bonded at the service entrance to the property. Again, the earths within the house are not
intended to carry current under anything but fault conditions, but as they are all bonded to the incoming supply neutral, they will work as normal current-carrying conductors if you connect a load L to E.
Finally, with TT there isn't a solid metallic path back to the transformer on the earth, but there will still be a path of somewhat higher resistance - There has to be such a path for the earth to provide its protective function. The transformer neutral is earthed, your installation is earthed to a local road, so you are likely to end up with an overall resistance over that path of a few tens of ohms to a few hundred ohms. You'll get a lamp or other load to light, but the resistance of the earth electrode connections in series with it will reduce the voltage across it - And cause the voltage of the installation's earthing system to rise. A modern TT system will have an RCD, so in practice this would not happen as the breaker would trip on what it (correctly) sees as an earth fault.