I completed an MSc in Public Health at the London School of Hygiene and Tropical Medicine a few years ago. There are a wide variety of jobs in this field depending on what you are interested in.
I would advise you to look in the Guardian newspaper, particularly on Tuesdays and Wednesdays, the bmj website and specific organisations that have a focus on Public Health, so this may be university websites, such as University College London, the London School of Hygiene and Tropical Medicine, Imperial College London etc. Also, the London Deanery advertises Public Health training schemes.
You might want to consider seeking some careers advice, there should be somebody dedicated to this at your institution. I hope that this information helps you.