I’ve always enjoyed simply being inside the M’O. I think you can exit and re-enter if you’d like to <<lunch/déjeuner>> nearby. The M’O has a dining room inside the museum. It has evolved over time from more relaxed/formal to get ’em and get ’em out. In 2012 I had a lovely <<lunch>> and was able to observe how things worked.
Again I believe wheelchair visitors are given seating preference in the dining room.
I intentionally took my lunch break very early, as soon as the dining room was available in order to avoid yet another queue. This was the lunch queue I saw on my way out.