I was recently (24hrs ago) diagnosed with a a chest infection and givens a course of antibiotics, painkillers and prednisone. am i contagious or can i continue going to work as usual?

Use precaution : Good handwashing, hand sanitizer and covering your cough helps to reduce the spread of infection.

Hard to speculate: Chest infections come in many forms. Viral, bacterial, & others. The potential for spread varies with the true cause, which is not provided in your information. Consider any at least as contagious as a cold & plan accordingly. Good hand washing and a face mask at work may prevent this from transfer to your co-workers. Otherwise ask the doc who treated you what to do.

Hard to say: I would act as if you are, but the real answer is difficult to say