Diagnosing instant circuit breaker tripping, with nothing connected
Here's what you're supposed to have. 

Live to neutral: some value of resistance depending on your load.  Don't be surprised if the figure doesn't strictly follow Ohm's Law; many devices have their effective resistance change after they warm up.   If there are no loads on the circuit, hot-neutral should be infinity ohms.  

Live to ground/earth: this should always be infinity ohms if the breaker  is switched off.  If it is not, you have a ground fault on either hot or neutral.  If hot-neutral is infinity ohms, then a lesser reading is definitely a ground fault.  

Neutral to ground/earth: should be zero ohms if the proper neutral-ground bond is connected, and should be infinity ohms if the hot and neutral wire are lifted off the breaker or neutral bus.

Non-infinite resistance (conductivity) between hot and neutral is normal if any loads are attached.  However, if you disconnect hot/neutral from the panel, there must always be infinity ohms/zero conductance between hot/neutral and ground.   If there is conductance between hot/neutral and ground, then you have a problem that you must fix.