If dash lights don't turn on when you switch on then definitely it is the switch. Changing the ignition switch is definitely an option but then you will have two car keys, one for the doors and other for your new switch. This switch should be repairable.
Even if the electrical contacts of the switch are non-repairable, you can buy a new switch and swap the electrical contacts part with the new one. This way, you will be able to use your original key.
It could be some issue in the wire connections to the switch. Get it checked from any good electrician. I have Cultus 2004 and it has never shown any such problem.