Where are you living // where are you working - london is expensive to live in but if you are having to commute to somewhere cheaper that costs money&time too
Can get cheap food from a big supermarket chain like tesco/asda/morrisons - if you are going to a small local grocers prices are inflated
Car
www.autotrader.co.uk
http://www.pistonheads.co.uk/sales/
don't forget the cost of insurance
http://www.gocompare.com/car-insurance/
http://www.comparethemarket.com/car-insurance/
and the tax disc which on some cars is ridiculously expensive
petrols not cheap either