This might seem a weird work around but if you be a ' bad ' employee and just don't show up to work for a few weeks isn't there a clause in your contract that they can terminate you. I mean if your goal is to terminate the contract surely you could do something that breaks the contract and basically forces them in a situation of firing you at which point after you're fired they're obligated to provide you with a termination letter ? Not sure if it's viable but just a thought.