John, I woud say you definitely want to be running in the aerobic zone, contrary to what was said. Save any anaerobic running to the end of the race. 10k and HM are different beasts and need specific training.
As Jools says, the long run is key (overrun the HM distance), supported by more easy running midweek. Get that nailed. Look to increase your lactate threshold with a tempo run once a Week - this will help you to run faster for longer
Its unlikely you will exhaust your energy at HM distance. I raced one yesterday, with an extra 10 miles steady running on top. Apart from breakfast, the whole run was powered by 1 banana, and of course a lot of steady training miles.