I'm heading to the Continent for a few days and thinking of using the Eurotunnel for the first time. When I go to book, it gives two hour time slots (1600-1800, 1800-2000 etc), so does this mean I need to arrive two hours in advance... e.g. - 1800 arrival for 2000 departure?

Any advice or tips received gratefully. I'll be driving through France and Switzerland, so guessing I need to keep to the speed limits too.