Outsider, have you ever considered learning online or on the phone? There are programs available for that. PartnersinTorah.com has chavrusas available to learn over the phone. Aish Hatorah has a program called Jewish Pathways that has online courses available. You can find them at Jewishpathways.com (original, right?). Anyway, the discomfort that you felt would probably get less over time if you continued to go to such a place frequently and if you attempted to dress one step up from jeans – say slacks and a decent shirt (not necessary to be in black suit). Yes, people would still remain distant from you, but once you become a frequenter of such a place, then once they recognize you as being part of their group the distance will slowly decrease.
Hatzlacha in whatever you decide to do, but keep in mind that orthodoxy is a matter of mitzvah observance, not how you dress.