Are there any websites which map light pollution levels so I know where to go for decent long exposure night shots? Or general resources for that matter?
Your distance from light pollution is very important when capturing any night shots including auroras. I would recommend using the Dark Sky Finder (USA only) and trying to be at a minimum darkness of the blue areas of the map. This means that almost the entire eastern United States is not a great place to photograph auroras! You could still do it, but it just won't be optimal with all of the light pollution. The lights only occur from about 50-400 miles above the earth's surface, so light pollution isn't quite as impactful as star photography, but it still plays a role.
Another option to assess light pollution is the Blue Marble Navigator, which works worldwide.
If you are interested in auroras in particular check out my previous answer here: What tips and advice do you have for photographing the Aurora Borealis?