There are a few ways to do this. All denpends what you are after. You dont need to create an automation but you can if you like. I do have another blueprint for the toilet and it is designed to work with this blueprint. Below are some options for you.
Option 1 - Manual Fan Switch
You can manually turn the fan ON and OFF but still allow for the automation to take control. First we need to look at your switch. If your switch is independent and not connected to control the fan then you can just add that switch into the “Manual Fan Switch”. If you switch controls the fan then you need to create a trigger-based template binary sensor and then use that trigger-based template binary sensor in the “Manual Fan Switch”. To do this I have a step by step guide in the FAQ click Here. You can also take advantage of the ‘Manual Fan Switch Auto OFF - Time Delay’ by selecting option 2 and setting your time delay. Then when you turn it ON it will automatically turn OFF in your set time delay 
Option 2 - 
Toilet Exhaust Fan with time delay blueprint.
The Toilet Exhaust Blueprint will allow you to turn the fan ON and OFF automatically. It links with this blueprint giving bathroom humidity BP priority. The Toilet Exhaust BP has a lot of features. Assuming your toilet is in the bathroom you will need to consider what will be the trigger for the toilet exhaust BP. You could use a distance sensor so when you are sitting on the seat it knows you are there or what ever works for you. I then have a FAQ step by step guide on how to link the 2 blueprints, click here.
It is really up to you on what you would like to do but ether way you don’t have to create any automations if you don’t want to just use my BP.
Hope this helps you.
Blacky 