You should avoid car finance at all cost. There are plenty of decent cars around that cost a few hundred pounds. There are also plenty of sites giving advice on how to tell which cars are worn out and which ones still have a few years' life left in them. Mine cost £300 about 3 years ago and, in spite of the abuse it gets, it still seems to keep going.
I don't know how old your car is but, if it more than about 10 years old, you shouldn't think about spending £1k on it. You'd be better selling it to a scrap yard for £30 and spending £500 or so on something better. If someone then comes chasing you for the finance, you could show them the £30 receipt from the scrap yard and tell them that you are not paying whatever thet are asking for a £30 car.
If you are shopping for another car, www.autotrader.co.uk is a good place to start.