OK, here's the word from flight ops at the CAA:
The rules have been clearly laid down for aeroplanes in the Part 1 documentation
EASA have not really got round to doing the same properly yet for helicopters in the Part 3.
So - the bottom line legally is the rule that you may only an approach to an airport which has been approved by the State administering that airport.
If you know for certain that the airport where you are landing has a "traditional style" non-precision approach published in the AIP, then of course you can fly it. (Of course you should also have a copy of the corresponding approach chart in your hand!)
If you dont know for sure that the state controlling the airport has specifically authorised it, then dont do it.
As we teach in the simulator to clients from dozens of different countries, and we cant know all the individual differences, the safest option is to say:
1. Make sure you have the correct approach chart.
2. Fly the profile depicted on the chart
Simple, really!
That is the line I am going to take - of course anyone who disagrees should take it up with their flight ops inspector, and see what he says.