Don’t fight prejudice with FACTS. This is NSCI guess that's a fairly common anti-immigrant perspective ("brown" people horrible/dirty, "white" people nice/clean).
Anyway, just to maybe reassure you.....my son-in-law is an immigrant. He is (obviously) married to our daughter, and he's in the UK under a spouse's visa. He has to pay over £1,000 a year in order to be able to access the NHS. His job (he works for the Bank of England) provides private health insurance, so he's paying for that too as a benefit-in-kind. Plus, of course, he pays tax and NI in the UK, so he's paying his due anyway. There may be a (very, very small) minority of people who get treatment on the NHS that they shouldn't be getting for free, but there are others who are effectively paying multiple times.