Be like a nike ad and just do it.

Soon you'll knock out 10 miles in 30 minutes and count it as the warm up before your ride really starts. If you're nervous about being so far just carry a small pump, patch kit, tire levers, spare tube, and cell phone/wallet. The only thing to really be worried about is a flat tire. Sure other stuff can happen or break, but it's really such a small chance you shouldn't be worried. Also get a little mechanical know how so you can do simple repairs, such as putting a chain back on if it comes off.

Have fun and enjoy it.