A carbon monoxide detector is not the same as a smoke alarm. Carbon monoxide detectors alert you to the presence of carbon monoxide in the air by flashing a light and sounding an alarm.
Ideally, you should have a detector in every room that contains gas appliances. If you have a gas fire in the bedroom, it’s particularly important to have a detector there. This is because carbon monoxide leaks are very dangerous when you’re asleep, as you won’t notice the initial warning signs, such as tiredness or dizziness.
There is no legal requirement for your landlord to install carbon monoxide detectors, but it’s a good idea to ask for one anyway. If your landlord won’t provide one, it may be worth considering fitting one yourself. You can buy them from most hardware or DIY shops for about £10. Make sure any detector you buy conforms to British standard BS7860.