Thanks Steve for the TPMS info - looked like it was going to add considerable cost to the wheels... however, the car had to go back to the dealer for what I thought was an issue with the balancing of the wheels (more on that in a bit), which gave me the opportunity to check with the technician what was fitted to the car - I have the 'run flat' system (standard I believe), which just determines if you have a flat tyre (no sensors in the wheel which check actual pressures) - He also advised the best way to tell between the two without having access to the menu's etc. He said if the valve is rubber you do not have full TPMS, if the valve is metal then you do have it.
On the subject of the balancing issue - I noticed a vibration above 65 mph, during it's inaugural trip down the motorway to show the new motor to my parents. I assumed it was a balancing issue due to the dealer (very kindly) putting on a brand new set of Conti's. But after taking it in today they did a load of checks and established two of the wheels (front left, back right) were warped....dealer is replacing them FOC next week. So glad I got it from a main dealer, but at the same time, concerned it slipped through their vetting process (as was the head tech!)
Back to snow chains... I'm going to get a set of 17" tyres/wheels from tyreleader, and the cheapest set of chains I can find just to satisfy the Gendarmes!
I was thinking black alloys - opinions? - car is Iridium Silver