How much is monthly health insurance?

It depends, as an insurer will give you a quote based on your age and medical history. To find the best price from an impartial expert you can first get some do some research.

Otherwise it's a case of getting recommendations from friends or contacting each provider individually for a quote. Depending on what type of cover you want and your medical history, cover can range from a couple of pounds a month to up to a hundred.