If you are new into this hobby, just purchased a drone or you looking to get into this hobby. Is really important to comply with UK regulations.
For Drones under 250g:
If your drone weighs less than 250 grams and is not a toy or has a camera, you are required to obtain an Operator ID. However, a Flyer ID is not mandatory for these drones.
For Drones over 250g:
For drones weighing 250 grams or more, you must have both a Flyer ID and an Operator ID
Link to get Flyer ID:
All you need to do, is go on CAA website and apply for Flyer ID and Operator ID , link: Click me.
While Flyer ID is free of charge, and you need to pass a test every 5 years on CAA website.
Operator ID:
You must be over 18 years old to be able to get the Operator ID...