OK, today I sorted out the fan.
I bought just the connector (Renault part number 8200729298), hoping that the resistor pack and other side of the connector would be usable (connector was damaged but not too badly).
With a LHD car it's not a 5 minute job anymore (in case there are any more LHD owners over here...)
The resistor pack is located in the same place as in RHD so you can't reach it from the dash opening.
I reached it from below after removing the glovebox assembly, for which first I had to dismantle all the center console.
I've been very wary about dismantling dashboards in French cars since I did it once to a 309 that I had, and bits of plastic were just cracking off everywhere, but I was happy to find that the Scenic II is better made, and was even happier to find that nearly all the screws I had to remove were the same size
I saw in the thread that when accessing from the top, it's recommended to pull the wires until something comes loose - so I have a pic of the bit that breaks when that happens.
Another pic of my connector as I found it, two more of the state of dismantlement I had to get to in order to reach the connector, and the last of the resistor pack side of my connector.
Thanks again to all who have shared their advice in this thread. I've probably saved hundreds of Euros