My Manager accuses me of being rude, but I don't understand why, since I did not speak much and there were no disputes. She has put in writing that she wants to speak with me about being rude, touble is this is likely to be during my appraisal. Was thinking of asking for a rise in salary, but is this out of the question now?

I would not ask for a raise during a meeting where you are be reprimanded for rudeness.
I would simply say you will work harder to improve your communication skills and leave the raise issue for another time.

Don't ask for a raise, ask for a definition of "rude." Does the manager mean impolite or did she mean uncouth?

Your job in this meeting isn't to come up with the right thing to say - don't try to talk your manager out of his or her perception of you. Rather show genuine interest in what they are saying, and plan to say, "Thank you for pointing that out to me, I wasn't aware I was doing that and will certainly work on it". Other than that, I'd suggest you say nothing. It's very difficult to accept criticism and our first reaction is to defend ourselves, but it's very important to learn not to do that in work situations and instead just absorb what we're told and improve as directed. Usually the managers will be right, sometimes they are wrong but never will they be talked out of their opinion. So even if the manager is nuts, you can preserve your job by acting like you will work on their concern - then look for another job before you get fired. If your manager has an issue with you and you address it to their satisfaction, you demonstrate that you can take criticism and will improve on request, which speaks volumes for you and will make a really solid, positive impression on that manager.

Once you've overcome the objection your manager has, and you have a positive review, you can then ask for a raise.