Switching from bottle to sippy/straw and warm milk to cold help

Okay I have a 1 year old just turned on July 24th he’s in daycare and a great walker even runs anyways he will start transitioning to the toddler room on Monday so I need some major help they do not allow bottles or warm milk in this class my son has a straw cup at home I introduced all these different cups by 6 months he took to this and drinks water out of it well mostly anyways when I try to put his milk in there he spits it all over himself and even gives me a weird look lol like uhh mom this is my milk doesn’t go in here ha anyways they started giving him a nuk soft spout cup at daycare idk why anyways they say he does great with it I think they are crazy or my son is another kid when he’s there because since they said this I tried it at home he won’t even tilt it to drink from it keep in mind this kid still and never has held his own bottle anyways I’m stressed about this move to the new class and getting him ready so any help would be so appreciated thank you so much and also what cup should he use should I tell them to stop confusing him and giving him other cups he has a straw cup there so idk why they did this also been working on the cold milk too thanks again