So the plan was to cross the channel, drive down to Grenoble, tackle the Route Napoleon to Nice, then continue into Italy as far as Florence, seeing a few other places in Northern Italy, then come back, making a two week trip.
When we came to get off the chunnel in Calais, the car wouldn't start. The lights come on on the dashboard as usual, but when you twist the key to engage the starter, the lights go out and the starter motor doesn't budge at all - the engine isn't turning over. Some kind guys gave us a push-start that got us off the train, and we continued down to Grenoble.
At first I thought it was the cable to the positive terminal of the battery. A few months ago I had the same symptoms. The cable had been extended for an FMIC install, and the joint was loose. It was conducting enough electricity for everything else, but when trying to turn the starter, the dodgy connection didn't allow enough current, and the starter did nothing.
However, after I had that problem, I had a guy re-wire that bit. I've checked the new connection there, and all seems fine.
I took it to a Nissan garage here in Grenoble, unfortunately they were just closing for the day (half day Saturday) so didn't investigate. But the guy said he thought it would be the starter motor, which they don't have in stock anyway.
The third possibility is the battery, although it is only 1.5 years old so perhaps less likely. Also, it isn't even trying to turn the engine over.
Its now Saturday lunchtime, and everything looks to be closed until Tuesday morning anyway (bank holiday Monday).
So if anyone has any idea for finding a garage that would have a starter motor for a 1994 180SX (SR20DET) in south-west France or northern Italy, then please let me know! Or any other suggestions for anything I can try, although I have limited tools here.