I have just got back from two weeks in France. We stayed in Haut Garonne- it is the bit between Toulouse and the Pyrenees. 1800 miles completed without a problem in our Sport. Things to consider for someone driving abroad for the first time, perhaps some of the less obvious. Motorway tolls. If you use them, the amounts can add up. We spent about fifty euros, mostly the section between Nantes and Bordeaux. Check your insurance: do you have the same level of cover in Europe as you do in the UK? Respect local speed limits, fines are now following drivers back to the UK. Have the correct bits and pieces in the car: eg have hi-viz jackets in the car, not in the boot. Overall, driving in Europe is pretty straightforward and a satnav is very useful for routing and finding destinations (obviously!)
Be realistic about distances: ‘Switzerland, Italy and maybe Spain’ covers an awfully big area. We spent three weeks a couple of years ago touring Spain alone and only scratched the surface. There are a lot of websites written by people who have done similar road trips, have a read of some and make a note of what seems sensible. Last word: spend more time seeing and experiencing than driving.
PS I forgot to mention air certificates. Each country has, or is in the process of, requiring carowners to obtain one of these for your windscreen. It shows whether your car is EU4, 5 or 6. Older cars are in for sizeable fees/fines in order to enter specific cities or even areas. It needs researching carefully. On another car forum someone entering Antwerp due to a diversion without a certificate cost35 euros.