Your best bet is to learn how to inspect a vehicle and save up a few hundred pounds. There are plenty of vehicles around for a month's salary in autotrader.co.uk, gumtree.com and your local papers.
Things can go wrong with old cars. My last one spluttered to a hault after 5 months, I was quoted £350 to get it fixed so I sold it to a dismantler for £200 (it had cost me £450). The replacement vehicle, bought in a hurry, cost £500. These are not large amounts of money and the sums are insignificant compared to the cost and hassle of car finance.