Hi, It is hard to say if she is just friendly or interested in you, but one thing seems certain that she does seem to like you one way or another. If you are interested I would say write the note as you said. This sounds like a good idea since it is discrete and as you said there are other sales people around. That would be best. Then you can take it from there. Another idea is to continue being friendly and make small talk then see where that goes. However, the downfall to that is it would take a little longer to see if she is interested, but would have more time being around you whereas the other way with the note you will know asap, but will have less time to talk. I think either way would work depending how anxious you are to go on a date. The good thing with the note is you can then know if you should try and forget about her in that way or if she feels the same you can start dating. All in all I think the note sounds good for you to know and go from there. I wish you well and please me know if I can be of further help to you.
thank you for your help, that was varry helpfule thank you mutch :)