You don't say where in Switzerland. If you assume Bern, the distance from Calais is 532 miles of which 526 is motorway. It will take you about 7 1/2 hours and the cost, for a car without caravan, is about 40 euros.
Try going out through Luxembourg and crossing into Germany and entering via Basle. No tolls unless got go down tio Metz and use the auto route to Strasbourg. Did itlast year and it was fine. You can get the Swiss toll ticket from their London office - buy it as close to your holiday as you can and that way get a reduced price for the year.