Could always take it to court, claim that you received your full licence in the mail.. and were none the wiser.. you MAY happen to get a judge on a nice day, play stupid and they could take it easy on you.. howeve i don't know considering they will be looking to crack down on P platers breaking the new laws..
imo i agree that the law is the law but 1 wk out doesnt make you any less of a driver.. you won't magically be able to handle a more powerful car..