Here is a typical heating circuit.
Bear in mind that before the switch (and CU) the N & E are connected together and
in the boiler are multiple circuits which in a combi will include the pump and valve.
This one is just WRONG as you have discovered (183Ω as there will be some connection between L & N in an appliance, e.g. oven element or just a lamp.
Also, a 'dead short' would give a reading of <0.05Ω and immediately blow the fuse when switched on.
Plus, of course, with PCB control in the boiler none of the parts will be switched on when the power is off.
This test is the useful one to ensure that the boiler carcass is earthed.
Further testing should establish that the Circuit Protective Conductor (CPC - earth wire) itself is actually connected to the Earthing of the installation (your 0.7Ω virtually does this).