Vauxhall Agila Brake Pads Problems

Soon as I start drinking theres a really annoying whistling noise coming from the car but if I press the breaks then the noise stop?? Any1 help

Will drive for miles without problem. When it becomes noisy, it can be quite loud. Pedestrians turn to see where noise comes from. Could it be a ball joint on steering? or wheel bearing? Is it safe to drive to nearest Vauxhall garage? It's ...