> I replaced our main thermostat which was pretty simple so guessing this would be about the same amount of work.

Sorry, that's not necessarily true. A furnace thermostat is a third party device designed to be replaced easily and uses low voltage standardized connections. Electric baseboard heater thermostats are usually line voltage high current devices that are double pole if used on a North American 240V circuit. Without seeing the model number (potato quality pic), or the wiring it isn't clear whether you have a low voltage or line voltage thermostat. If you are capable of safely replacing an outlet, you can probably replace this thermostat. The Honeywell Home CT410B is an example of what you may need.