Lenses for Olympus e-pm1 - total newbie!

I am a newbie who recently purchased a Nikon L810 on recommendation from a best buy employee (boo) and returned it shortly, because I was severely disappointed with the image quality and was struggling with the lack of adjustable settings (everything was pre-set modes). I kept getting noisy shots in all lighting conditions with all shooting modes. If all I am going to get is a mediocre shot I could get with the camera on my phone, there's no point to spending all that money. Now I know (after reading a lot of forum posts) that it has more to do with the user than the camera, but I still don't see the point in carrying around a separate point and shoot camera when there is a decent one built into my phone. If I am going to spend the money, I want there to be the potential of good image quality.   I digress......

After doing quite a bit of research on entry-level dSLR cameras (Cannon t3i, Nikon D5100) and several mirror-less interchangeable lens cameras, I finally decided and have an Olympus PEN E-PM1 on the way. I was looking around at different lenses that are compatible and they are pricey - more than the camera! I knew that, but still....it hurts my bank account just looking at it!

Finally to my question: Is there any kind of adapter so that I might be able to purchase a slightly less expensive zoom lens and still attach it to the e-pm1? If so, what would you recommend? If not, which lenses are actually worth the money? Do I even really need a zoom lens? I'm going to Mexico for my brother's wedding in about 5 weeks, and want to be fully equipped for fully capturing the trip.

Thank you in advance for your advice! Sorry I'm long-winded!