jondc9
made a pilot report of actual runway visibility from the aircraft.
you cant do this in Europe.
If you think the IRVR is wrong best you can do is try to persuade ATC to send someone out to do a manual reading (count lights) this would probably take 30 minutes plus to arrange. A JAR OPS manual would have a phrase something like "regardless of whether the runway can be seen a visual approach may not be continued below 1000' if the reported RVR is below xxx(800) meters."
So in your scenario, we get to 1000' AGL on the ILS and the RVR is 300m we cannot continue the ILS because of the approach ban, but we see the runway so we call visual but we cannot continue a visual approach because of the approach ban.
The regulation is there to prevent people either
A: lying that they can see the runway or
B: flying into sucker gaps in the fog.