There are plenty of websites which will try to tell you that such penalty charges are not enforceable but some people have found, to their cost, that they are:
http://www.rochdaleon...alty-in-landmark-case
However it should be noted that car park operators can only pursue the DRIVER of a vehicle for payment of the charge, whereas the information supplied by DVLA relates to the REGISTERED KEEPER of the vehicle. (Unlike, say, speeding fines there is no obligation upon the registered keeper to reveal who was actually driving the vehicle). Some people maintain that it's possible to avoid payment of such charges by simply stating that someone else was driving the vehicle. (Whether that would work or not would, if the case came to court, depend upon whether the court believed - on the balance of probabilities - that your statement was true).
You MIGHT also be able to contest the charge on the grounds that the 'disabled parking' markings were obscured but a court might rule that (given the presence of signs warning about parking charges) your girlfriend should have taken greater care to check where she was parking.
Chris