If you have shit credit a loan is likely to be very expensive and if you have no savings, chances are you can't afford to pay a loan back.
Could you borrow a bit of money from your parents or another relative to buy a cheap car - say £500?
Are there any weekly tickets etc available? Could you cycle?
Can you have a week off work to save a bit of money on transport? Can you cut right back to the bone for a couple of weeks or so - literally beans on toast, reduced food, sell anything you can, see if you have any credit on your utilities that you can get back, to free up a bit of money to buy a cheap car - but if you do buy a car, make sure you check the tax and insurance costs, as tax can be as little as £0-30 a year for a small cheap car, or as much as £300+, so you don't want this type of car.
Also insurance - you want one that's as cheap to insure as possible, so do some dummy quotes before committing, it can literally vary by £000s.
Also don't forget the cost of repairs. Expect to spend at least a couple of hundred pounds a year on repairs and put the money aside - if you don't have these costs, you're onto a winner, but if you do, you have the money ready and won't be faced with having a knackered car that you still have to pay the tax and insurance on, but having to find the bus fare on top as well.