Are you in privately rented or with an agent? It's the landlady's responsibility to have a Gas Safety Check on the property each year and if this would of been done it would of been picked up as you say you have been living there 3 weeks, Its done yearly and its a legal requirement if she's renting properties.. If she doesn't have one then she can get in serious trouble, you should of been handed a gas certificate before moving in that tells you everything that has passed or if its failed, if anything fails they shouldn't allow you to move in until its fixed.
I work in an estate agent and its against the law to rent a property without a gas safety check.
Hope everything's ok x