Assuming you've got the standard suite of vaccinations for the UK, you'd be screwed. While some of the jabs you've gotten would be quite useful -- MMR and DTaP -- there's a whole suite of illness to which you would have no protection. Barring certain military/medical service, you probably haven't been vaccinated against smallpox. Nor have you probably received the (less than optimal) TB vaccine. Both of those diseases were present in 17th Century England.

Also present in England at the time, and particularly in East Anglia and the Thames: Marsh Fever, aka malaria. Bubonic plague was also endemic to England at this time and the Restoration is particularly famous for the Great Plague of London. Being completely naive to the disease, you'd be at extra risk for infection and death.

Then there's the sanitation. An epidemiology professor of mine like to say that "The whole world is covered in a thin layer of feces" and that goes double for a society with no knowledge of germ theory. At best you could hope for some (time) traveler's diarrhea, but you would also have to worry about Hepatitis A and various parasitic infections. This paper is actually about 17th Century Colonial Newfoundland, but it's easy to imagine that a bustling metropolis like London would have even more opportunities for obligate human parasites like hookworms and tapeworms to spread through sewage-contaminated water and fecal-contaminated foods.

And for the love of God, be careful who you have sex with, unless you enjoy the side effects of mercury treatment.

If When you did fall ill, you would at least be doing so at a time when professionalization and standardization of the medical profession/education was in full swing. unfortunately, Hippocrates and Galen were still the "standard" and were only gradually falling out of favor in deferrence to modern medical practice. Bleeding and purging, in other words, were still standard of care along with various herbal treatments which seem bizarre today. Nagy and Evenden, for instance, record a university trained physician treating a case of "falling sickness" with round pieces of peony root hung about the neck and sponges of vinegar and rue applied to the nostrils.

Barring you travelling back in time with some disease that emerged in the modern era (e.g. AIDS, SARS, Ebola), you would most certainly be at greater risk from the average 17th Century Londoner than you would pose to them.