Police have exemptions for hand held devices and are trained to use them whilst driving
If using a CB causes a safety issue then the driver can be done for not being in full control of the vehicle - same goes for eating an apple for example
It’s not illegal to eat while driving. However, if you get distracted while snacking behind the wheel, the police could prosecute you for careless driving if they consider you to not be in proper control of the vehicle, an offence which carries an on-the-spot fine of £100 and three penalty points.