I recently sublet an apartment short term, and now I want out for various reasons (apartment left really dirty, damp only able to use one of the bedrooms instead of both as agreed). It would mean leaving the agreement early, my question is, what does it take for a sub-let arrangement to be legally binding? The piece of paper we signed was very makeshift (i.e. written up in less than five minutes, with no lawyer present, and the person I agreed with isn't even the property owner). What is my legal responsibility in this case?