Central heating is normally turned off during summer. For electricity just make sure nothing is plugged in, set your fridge thermostat to a minimum, and no appliance on standby except if you have home security camera.

Even if you leave during winter months you should not turn off completely the heating (lower it a bit instead), as your apartment will be cold and moldy when you come back.

For the electricity, unplug anything unused. Don't switch off the central electricity as you still needs the freezer and fridge to function!