Cat - have you thought about leasing a car? My friend has just done this - she flew into a complete rage at how much money she had lost when she sold her old car, so is now leasing. Takes care of tax and MOT
I think all you have to pay for is insurance and running costs. If anything goes wrong, she just phones the garage and they deal with it / pay.
To be honest, shes finding the whole thing fab! Am not sure how much she pays a month for the car. No gut-wrenching depreciation to angst over, though!
Im not sure how much ours costs to run, I leave all that to DH!
Id recommend, if buying, that you look at fuel consumption as this is what can turn a car into a money guzzling nightmare. Also look at something that is a decent enough size for you and your family to grow into. Maybe a Polo or a Golf?