Braking fault on dash

Every morning on my way to work at roughly the same sort of time I get "braking fault" flash up on the dash briefly and then go off again. I've also had 'check esp' flash up on the dash too. My mechanic checked over my braking system and couldn't find any leaks, plus my scan tool doesn't find any errors. Anyone have an idea what to check/replace next?

From what i've read it could be a wheel speed sensor, abs sensor or brake pedal switch?

Any help appreciated, thanks