Do we need to add a comma before "as"

Despite all these comments, no-one has attempted an answer. Since I disagree with most of the comments, I thought I should give this answer. Please note I am a native BrE speaker.

If you wish to be very polite then you might well choose "would" rather than "will". In the context of a student addressing a professor, politeness might be appropriate. The element of doubt implied by "would'" permits a polite withdrawal: the professor might change the timings; you might decide that you could change your other commitments. "Will" could be read as an ultimatum.

There are a few occasions in which the omission of a comma changes the meaning of a sentence. This is not one of them. The modern taste is for minimal commas.