Good morning
it will be a little late for immediate advice at this point but for future reference it is important to find out if it is your smoke or your co alarm that has gone off. I'd advise to test both units to familiarise yourself with the sound of both units.
Smoke alarms can false alarms if contamination in the smoke chamber (dust, small insects etc) occurs but co alarms normally don't false alarm.
Follow these steps if alarm sounds:
1. Keep calm. Open all doors and windows. Turn off all fuel-burning appliances if possible.
Note: Outdoor conditions could influence domestic CO alarms (bad traffic
pollution in cold weather, for example). In these circumstances, the level of indoor CO might
actually increase when doors and windows are opened.
2. If alarm continues to sound, even after being reset (where appropriate), evacuate the
premises, alerting other occupants to the risk. Leave doors and windows open. Do not re-enter premises.
3. Get medical help for anyone suffering the effects of CO poisoning, and advise that CO inhalation
is suspected.
4. Call Gas Emergency Services: 0800 111 999, or your local Gas Safe Registered Engineer.