Many galleries aren't open on Mondays, but for those that are, I'd suggest just popping in and trying to meet the owner or manager. But here's the challenge, most business owners don't want to be approached by sales people, especially without an appointment.

I remember when I managed my family's gallery; it was much easier to talk to an artist if she came in as a customer first. For example, if she said hello, took some time to look around a bit, and naturally struck up a conversation with me about a piece of art or the history of the gallery, I would already have a positive, baseline connection with her.

At that point, if she casually mentioned she was an artist, I would be more apt to ask her about her artwork and want to see some of her images, even without an appointment.
Unfortunately, what would usually happen is this: an artist would walk off the street, slap a briefcase down on the counter, often interrupting me making a sale with a customer, and shove slides or a marketing kit in my face.

Here's a tip: when you start to talk about you and your art, try saying something like, "I happen to have some images of my art in my (fill in the blank: car/purse/briefcase). Would you like to take a look?"

If the gallery owner declines, don't take it personally. If the owner asks you to make an appointment for a future date, respect that. And if the owner asks you to share your images there and then, get down to business!