No you won't. I promise! You have me and Hawk to ask for help! I never tried the D3 editor, but I was much younger and less determined to map. To be honest, KISMET seems a lot harder than it is, but then again, I only used KISMET to make doors move an such. On top of that, there are a lot more resources to help you out with UDK vs D3 editor. I started with World of Level Design, but then I realized how cursory that information was...after I made my first map out of almost pure BSP.
Don't worry, if anything, I'll be here to walk you through any questions you might have.
Once you download the UDK and are acquainted with the interface, PM me here or on the SolC website and I'll send you my last map, Triaxiality as well as some other assets that got me along so you can dissect them as you want. I found that I learned so much more by seeing other people's maps than by experimenting on a blank map because it gives you a point of reference.
If you make it in as a team member, you'll love yourself for trying: having access to 6DoF in UE3 is so rewarding and just awesome in general. I can't wait to play-test my laser cannons on other devs