may i ask when you going on your hol's ?
we are going on a road trip this year to rome via. france,switzerland,
we are so confused about the road tolls, i've evn e-mailed Top Gear to see if they can help!
If you have any ideas on the prices through France/Switzerland and the best routes to take can you please pm me???
Cheers 
The best way to go to avoid the tolls in France is to go via Belgium, when Luxembourg, when Germany, going this way you wont have to pay a single toll until you get to the Swiss Border at Basel, then exit Switzerland just North of Milan the Tolls in Italy are Expensive

And the tolls both are for left hand drive cars so make sure your passenger has the cash or credit card
.Use this website, its the french motorway website tells you all the toll charges
http://www.autoroutes.fr/en/homepage.htmlFrom : Calais (62, France)
To : Rome (Italie)
Itinerary : Express Vehicle : Sedan car
Distance : 1678.6 km On motorway : 1655.3 km
Duration (1) : 15H47
Fuel : 185.90 € (143 l)
Tolls (2) : FRA : 45.40 EUR
CHE : 40.00 CHF for 1 year
(1) Apart from taking breaks, normal conditions (trafic and weather)
(2) Apart from toll bridges and tunnels out of France
And the ItailanTolls:
http://www.autostrade.it/en/index.htmlPlan your journeyfrom Varese to Bivio SS4 Salaria
Length: 627.0 km Driving directions »
Average travel time*: 6h 57'
(*) Average travel times, evaluated on statistical based at a speed of 90 km/h
Toll amount for cars and motos: 36.70 €
Tolling is partially calculated by km (555 Km) and partially is
All this info is for a one way journey