No, she's not - so far as the Church of Scotland is concerned she is just a worshipper. It's only in relation to the Church of Englandn that she has any special status.

I suppose it might be possible to claim that there was an exemption for the monarch by virtue of her/his role as Supreme Governor of the C of E. But that couldn't extend to the stuff about "advisers" in other capacities.

Incidentally it's only Catholics affected here - if a British monarch wanted to marry a Hindu or an Moslem or a Jew or a Scientologist, etc, no problem on these grounds.