Good grief... I think the rain and fog is getting to people already.
GO get some sun SOMEPLACE if that's the case, or talk to your doctor about SAD.
Meanwhile, the cheese used is generally "classic American Cheese" which is usually a mix of Cheddar and Colby cheeses. One of the varieties of pre-sliced supermarket cheeses here is pretty close - Edamer cheese - which is available at Coop and Aldi for sure.
So far as that "schmelz käse" stuff, bleh. Yes, it's melty and it tastes alright on a grilled cheese sandwich or "toast hawaii" but it is nasty to eat on it's own.
If you're looking for a cheese that will take the flavor closest to a McD's burger but you can make at home, go with the Edamer.