Hi Subo
You are completely correct about the spare wheel (but check first to see what you get in case the situation has changed)
The problem is worsened by the fact that spare tyres of the correct size are not readily available "off the shelf". You'll probably have to wait for an overnight delivery (don't even think about weekends or Bank holidays). The situation will probably be worse in France which alarmed me.
I understand that the problem basically comes down to the wheel size (17inch x 6.5J) which is only used by Nissan.
As you say the spare is a 16inch x 6.5J steel wheel. it appears to be impossible to source a 17inch x 6.5j steel wheel for the spare.
Nissan will supply an alloy of the correct size priced at almost £600 plus the tyre. It is possible to buy new a 17inch x 7 alloy wheel for around £100 (plus the tyre) but I'm not sure about having different size wheels as regards legality, road holding and whether there is sufficient space in the wheelarch for a slightly larger tyre etc
Two of us managed to get around the problem by purchasing second hand alloys from a scrap dealer (after a lot of searching by JohnG). They are Easy Jap parts at
http://www.easyjapparts.co.uk and cost £188 including delivery. Both had reasonable tyres. They were from a late 2007 model, 6 spoke and 5 stud but a slightly different pattern (the different pattern isn't very noticeable once fitted on the car). It is vital they are identical size to yours if you buy one. They are in the West Midlands. I drove up to get mine so's I could measure it up and compare it before buying.
Scrap wheels may be easier to get as more vehicles are involved in write offs.
And yes, it does fit in the spare wheel well.
Xacre