Hope your mum is doing well.
Why are you worrying about the car, surely she had fully comp insurance (it's new car..) and the fact the car is new and the curcumstance of the crash she'll get top book for her car. ie vaule of new car or they will source new car for you (ie they pay a bit less for it)
Take a Civil action against him, get her to call up a Accident based solicitor and see what they say, shame your in england as i know of a very good scottish one (RTA Scotland). There has to be the same thing down there.
As for charges, he will most likely be admonished for driving with insurance (they always seem to get that) but will most likely get more than a years ban and at least 500 quid (unless he is in financial hardship).
If your mum has had to stay in hospital overnight a few times (which i assume is yes) this will be taken in to account and He will get extra for injuring her but that all depends on the the judge(s), how he's/she's feeling, what side of the bed he/she got out of and the like, IE could be anything might get a week in prison but might only get a larger fine (i've heard of it go both ways) my mate works at the Proculator Fiscal i'll ask what he thinks, (Scottish Version of your Crown Pros.)
Who told you he wasn't insured, as i've heard cops say that before as your "techinally" not insured when you drink drive, but he might still be.
I'd deffinatly check he is or is not insured.