Choc Chip , I have been there too with stress at work and its terrible, You will feel better when you have settled again somewhere else,
if you are paid sick leave and have no intention of ever going back then ride it till the cash stops, failing that if you are not paid sick leave tell them the job has made you ill due to whatever the facts are , tell them you do not want to work your leave but are giving them notice.... Just tell them thank you for employing me and say you are sorry for being made ill by the job , that way if a referance is sought by another employer it should come back reasonable....
I hope you bounce back with vigour as I did , Happiness is worth far more than money , I took a 10 k drop to be happy , one life , live it ........
Best of luck choc chip .....