Your property should only be disconnected from the gas supply used for hot water and heating in an emergency, but when a property is empty the gas supply is sometimes capped to prevent it from being wasted. If you have just moved in and have no gas supply, hot water or heating you should speak to your building management or landlord, who should be able to remove this cap.
If you have a pre-payment meter and you run out of credit, your heating will stop. You can top up your meter through the app or website of your supplier if you have a smart meter, or otherwise through a key or top-up card that you will have been given when you moved in.
Otherwise, if your supply of hot water or your heating system stops suddenly it is likely to be a problem with your building supply or boiler. In this case, you should reach out to your landlord or property manager.