You should get your brakes inspected every 6 to 12 months, for example during regular maintenance, during the yearly MOT the brakes are checked as standard. That said, when a brake warning light or brake pad wear sensor lights up on your dashboard make sure you get the get brakes inspected as they can point to an issue. Most modern cars have a brake pad wear sensor that will light up on your warning dashboard when it's time to get the brake pads (and brake discs) replaced.
However, the brake pad sensor cannot detect and alert you of problems that can occur with other parts of the braking system. So even though you've passed the MOT check and have done an annual service, brake problems can occur in the interim. If you're a regular driver, it is recommended to get your brakes inspected more often, for example every six months or every time you do an oil change.