At my Bridge club, we have a large playing area that can accommodate 250 or so people. There are four exit doors and located at each of these there is a break-glass callpoint thing plus a 4.5 kg ABE dry powder fire extinguisher. When someone discovers an alarm, the first priority is to trigger the callpoint so that the evac signal sounds and the fire brigade is notified. What is the next highest priority thing to do if the fire is small enough to be tackled with a fire extinguisher - is it 1) try to put the fire out with the extinguisher - or 2) race around the building making sure people are evacuating - or 3) call the fire brigade on 111 and tell them what’s happening.
Depends on the size of the fire, a small fire (like a toaster, microwave, computer or light fixture) (( make sure you get the proper extinguisher)) you should use the extinguisher for those.
Yet for large fires, such as oven or large appliances, wall on fire, evacuate everyone and make it the first priority to activate the alarm.
Next I would evacuate myself and others by my exit.