We need a little more info about this "hypothetical" situation. Firstly, what makes you suppose that a sawn bone you've found is human? Can you be sure that it isn't just a leg of lamb or beef that a family gave their dog to chew on after they've eaten most of the meat? If I saw a sawn bone I'd automatically think butcher, but then my life isn't very exciting that way.
The second thing is, how can the finding of a bone be connected to you losing your driver's licence? This is a driving licence, right? Presumably you'd have to be out of your car to find the bone. I just don't see a connection there. Unless you found a human bone in your car, in which case losing your licence is the least of your problems.
Did you remove the bone from the scene? Because that could get you into some trouble. And if not, can't you go back with someone else who's not violating their licence (I still don't get it) and "discover" it with them and call it in? If so, I guess you can just replace it and still rediscover it and call it in.
Whatever the situation, if you've found something that you suspect is a human bone then you have the responsibilty to call it in to the authorities. They're not going to stitch you up for minor offences if you lead them to the scene of a serious crime like murder. You did say this was hypothetical, are we talking about a dream you had?