Hi Brokegirl. Have you checked your sums on the this.
50c a mile seems a reasonable milage allowance and should allow you to actually 'make' some money. Assume you are only doing 1,000 miles a month. thats €500. Estmate petrol at 7 euro a gallon and 30 miles per gallon. Thats 233 paid on petrol. Assume car tax at 400 and insurance at 600 per annum = 85 euro amonth. So your employer is 'contributing' 180 amonth towards your repayment + depreciation. But these are 'sunk' costs which you would have anyway,as I guess you still need a car, whether you have this job or not.
I am sorry to hear of your separation and associated financial difficulties, but perhaps these are clouding your views on your job. You will not be better off on SW.
Please investigate the 3 day week option further, and maybe a relative would lend you the tax and insurance money, in the short term
( Your employer being slow paying your expenses is not acceptable)