A simple basic heater simply plugs into a standard socket and so as long as you feel confident about safely mounting your heater to the wall, stand etc. you don’t need to employ an electrician.
If your heater installation is above 3kW, or you are linking multiple heaters then YES.
When using a 3kW heater in commercial premises or other locations where the heaters are used continuously for long periods of time then it is advisable to consult an electricitian. A 3kW heater used for long periods of time may need to be hard wired into a 20A fused spur rather than used in a standard 13A socket.
