bill covers. Your overall account balance will also inform you if you're in debit or credit to E.ON Next. This will help you see whether or not your direct debit is at the right level to cover your energy usage.
I wasn't able to take a meter reading till now, but while talking to eon heat they let slip the meter progresses itself...and mine has an E before the figures, does this mean estimate? Always use immersion heater, as first person said, and they told me, this means eon heat is not...