If you need to take your car to France, seriously consider the Eurotunnel. You may have to try a few different departure times and dates to get a cheap price (we paid £34 for a day trip), but it’s worth it: 35 minutes from platform to platform, a very comfortable ride, and when you arrive you just drive off with no waiting (customs is all done at departure). I hope never to have to get on a channel ferry ever again.