Forgot to cite a quote

Hi,

I just handed in 4 big essays a few days ago. I realised now, after reading through it for probably the 7th time that I have forgotten to add a footnote to a quote. This quote was taken from a novel, (it is for a literature module), I have added footnotes to everything else from that novel and other works, and it is clear that the quote is taken from that novel - it is included in the bibliography.

I was sure that I had provided footnotes for everything - but I got some problems with page numbers because I was switching computers, and converting from Openoffice to Word document when I was printing, so everything with page numbers, etc. ****ed up. I have either forgot to add the footnote when I was typing, or I have deleted it when I was trying to fix everything else.

What do you think the consequences will be for this? Will I be accused of plagiarism or will I just lose marks - and in that case, how many marks do you think they will deduct?

I'm a bit stressed out now - read through the work so many times before I handed it in. I can live with losing a few marks, but I'm a bit scared of being brought in on plagiarism charges.