Basic life support are the actions that will maintain breathing and circulation on a person who is in cardiac arrest until further help can arrive.
According the Resuscitation Council UK, effective CPR more than doubles the chance of someone surviving.
There are great online resources available for free to help you learn or to refresh your skills.
Lifesaver is an interactive film by Martin Percy, where you are put at the heart of the action and need to make crucial decisions and learn the essential skills needed to save a life.
Join in and learn with the Resuscitation Council UK online via: https://www.lifesaver.org.uk/
Not sure how to use a defibrillator? The Resuscitation Council UK also has a short animation where you can meet Defib Dani to learn more about defibrillators: https://www.youtube.com/watch?v=7aX1EwkC1yY