I read all night and I have a partial Author Rec coming for you as soon as I get the chance. In the meantime let's get you aMerlin/Arthur Canon Era/Modern Time fic.
Today is Tomorrow and was Yesterday, by
rotrude ; NC-17 ; Three Parts ; 22k words
A/S : Merlin uses his magic to save Arthur and himself from the clutches of an angry monster. Something goes wrong and they find themselves whisked off to modern day London.
This is a very nice timetravel fic. It deals very nicely with how it is to arrives in a modern city without knowledge and ID and cards and such, and the relationship between Merlin and Arthur resulting in it is greatly despicted. I also love the sex scene at the end very very very much. I find it reeks with love and care and tenderness and this is a delight to read.