I like @davesparks method. I'e what i always believe to be the standard way of finding an IR fault.
Nothing wrong with that, but I'd take advantage of the known continuity of the ring to save opening and disconnecting stuff. I would inject a current around it from a small ELV benchtop power supply that can operate in constant-current mode into a short-circuit.
First I would go to the CU and hook up the PSU to circulate say 5A around the ring neutral from leg A to leg B. I would tie the ring line to neutral at leg A so that the voltage along the neutral can be read at every socket without a wander lead, just by plugging in a voltmeter with a 13A plug adaptor. Each metre of run between CU leg A and the socket would add 38-40mV to the reading.
First I would measure the voltage between leg A neutral and the lighting neutral at the CU, test (A) in the sketch, to find out the voltage present on the ring neutral at the point of the interconnection. Then I would walk around the ring doing test (B) with the plug adaptor, looking for a socket showing the nearest voltage to test (A), which would be at the point of interconnection. Or, if it's midway between two sockets, those with the nearest voltages above and below test (A).
At this point you will know the location of the problem on the ring without having to access any lighting points. If it's not then obvious which lighting point is involved, it would also be possible to do the same test using VD along the lighting circuit, but it would need shorting L-N at the far end or a wander lead running out to it, to serve in the same current injection role as leg B of the ring.
This probably sounds a bit long-winded but I would say with a dozen points on each circuit, so long as I could get to the sockets and lampholders / roses, I would guarantee to have found the nearest point to the interconnection within 20 minutes, without undoing a single screw other than to open the CU. Although the PSU would be 'energising' the circuit, it would only be with a volt or two, so none of the tests would be hazardous. It would not matter if a few small hidden loads remained connected to the circuits.
In another thread I will tell how I used this method to trace a fault in a completely inaccessible circuit with 20 points, on location on the beach in Amalfi, using a brake light bulb and an alarm battery as my constant-current source.