"May I have a coffee and sliced bread, please?"
Translation:Puis-je avoir un café et une tartine, s'il te plaît ?
Why isn't it j'avoir? Since obviously, because of the written words already there, this could not be in the answer you wanted, I wrote "Puis-je, s'il vous plait, avoir un cafe and une tartine." Why can't that be correct also?
The "question+infinitive" structure is never connected (although it is pronounced as though they are connected in fast speech). When you put s'il vous plaît in the middle of the sentence like that, it just makes the sentence sound a little stilted and weird. I think it sounds weird because it splits the auxiliary verb (puis) and the infinitive -- I would never say that.