If you have secured the monk keys from the back room after being thrown out just clinb to the top of the construction thing and jump down onto the roof but bring bandages and healing potions it shouldnt kill you but it will fuck you up. Then just find antonious (the pious) and kill him then use the monk key to run out of the back exist. Go down to the cellar and its the last door in the back. Thats what i did when they kicked me out. I will say though if you dont have the monks key you will have a difficult time getting out.
Just so you guys know. If you paid attention, you would have known who it was after you talked to the scribe in Rattay, he tells you 2 names there. Some Anton from … and Reeky from Ledetchko. You could storm in, kill Anton and leave. Or go shoot from the being build church top and hope you hit the right novice.