Hi Suzanne.
A great site to look up info about Darlington would be UpMyStreet:
http://www.upmystreet.com/overview/?l1=DarlingtonYour three years will go by really quickly. I've been here more than six and there are still things in the garage I haven't unpacked. I'd vote for you to store most your big stuff in the US until your return. You can rent furnished places, and you certainly will want to give consideration to renting electrical things because you won't be able to use them after three years. (I mean bigger things like a TV or washer, etc.)
The thing about moving your stuff is that you'll putting them at risk of being damaged/lost/stolen...three years just isn't worth losing something that means a lot to you. I would, however, bring a few smaller/special things to remind you of home. You'll never lose your roots, and sometimes you might find yourself missing something that you can look at/hold to bring back some memories.
Oh gosh, I don't mean to make it sound as though you won't having a thrilling time here. It's a fabulous opportunity for you! I LOVE it here and have certainly made it my home. I finally feel like I have found where I belong. However, during those first three years, it did help knowing I had something "from home".
So, what I'm trying to say ...

... for practicality's sake, don't bring over too much; it'll just be a big hassle. For sentimentality's sake, bring over some reminders of home and who you are.