If you have a car that is no longer worth repairing then you may consider scrapping it. There are nay companies out there that will scrap your car for you, they will even come and collect it, but they will only give you the weight in scrap which is often between £50-£150 depending on the weight of the vehicle.
If you really want to get the most out of your car then you need to be prepared to strip it down yourself. If you have somewhere to store the vehicle, then you can literally sell everything on it, down to the badges. Places like Ebay and Gumtree are good places to start selling car parts and you may be surprised as to how much you get for them. A set of alloy wheels that are in good condition can fetch upwards of a hundred pounds alone. Even the washer bottles and battery can get you another twenty or thirty pounds. Very quickly you will be able to get back more of your money by stripping it down and selling it this way rather than selling it to a scrap yard as a whole.