Corsa sxi heating problem

Ive just bought a corsa sxi on a v plate. The fans are blowing in the car but the heaters are cold. Ive checked the water and theres plenty. Ive got a rough idea about engines. Can anyone suggest what the problem could be? Im also getting the orange electrical fault light coming on I dont know if this has anything to do with it ( maybe the thermostat? ). The car had also been standing for a year. Also the tempature gauge in the car is not working