As I found out recently, when you go to renew your CAA Operator ID, you will be asked to complete a new test for your Flyer ID as well, even if your five years aren’t up. This is because a number of the regulations have changed, like the UK0, UK1 labelling and needing to show a green flashing light at night, etc.
The latest regs can be found at https://www.caa.co.uk/media/csmfqbs1/the-drone-code-march-2026.pdf