See also "iDBUS numéro 1" (read again)
En avant, à Paris
iDBUS offers an extensive network ...
One on-line article is positive about an iDBUS journey from London to Paris:-
When I arrived, the two drivers were friendly and bilingual; they checked my ticket, took my luggage, and welcomed me on board. The coach was spacious, had free wi-fi and power outlets, and the seats reclined pretty far back. It was quite comfortable as far as buses go.
I’m not entirely sure what the Eurotunnel is [the writer, "Expatedna", is youthful American, touring Europe; 'nuff said!] as I fell asleep almost immediately after we started moving, so I really can’t say.