Welcome MrO!
++1 to both of the above.
-Also take your time to sanitise and rinse anything that will come into contact with your brew, I even do the tin opener and also peel the label from the beer kit tin and then give it a dunk into the sanitiser too
- When topping up your FV with water to the brew volume (20L is best for Coopers), start checking the temperature from about 15L onwards, to make sure that it ends up between 20-25C for pitching the yeast.
-Don't be surprised if it takes 24+ hours to show signs (foaming) of fermentation, and then try and leave it alone for 7-10 days at around 20C ambient to do its thing.
-Lastly (should be firstly), remember to take a hydrometer reading of the full brew volume before you add the yeast. This reading is called the OG (Original Gravity), and will help you work out the ABV % of your brew before bottling/kegging.
Good luck and enjoy!
MB