Eurotunnel experiences

I am thinking of booking a trip to France using the Eurotunnel. Does anyone have any experience of this and let me know what its like getting on and off and during? What are the cheapest days to travel on? Also, I have looked at the documents regarding propane bottles but am still unclear, can I drive on with 2 full 19kg bottles of propane gas?

My first post here, hope its a good one!