This is complicated to compare. One advantage of the UK system is that it's quite clear how much tax you're responsible for paying. That transparency with regard to healthcare costs simply does not exist in the US.
But looking at your scenario: if you're unmarried and have no family, you'd probably pay around $10k in federal taxes per year. As you noted, state income tax in Florida is 0%, but that will not affect federal tax rates.
Most Americans get health insurance through their employers, so what you would pay for that is entirely dependent on what they are offering. See my previous post for average numbers per family. But let's say you're looking for private insurance yourself. Looking for a specific example,
this cost comparison site shows that the cheapest "platinum" plan in Florida would cost $549/month for a single 40 year old (less if you're younger, more if you're older). The average platinum plan is $822/month. So total cost of taxes and healthcare per year in the best case scenario, about $16.5k.
That isn't the real total cost, though - googling the name of that platinum plan provides
this handy pdf outlining further costs. The deductible for this plan is $1000 - this is the amount of money you have to pay before the insurance covers anything. For most major procedures there is a 10% coinsurance charge - this means that above the $1000 you pay, you're still responsible for 10% of the cost, while insurance pays the other 90%. There is an out-of-pocket limit of $3500, so above this, the insurance plan pays 100% of costs. So we can potentially add $3500 to the previous total cost of taxes+healthcare to get $20k. You're now paying a third of your income per year on taxes and healthcare.
But that's not all! That $3500 out-of-pocket limit only applies to hospitals and doctors that are in your insurance provider's network. If you go to an out-of-network hospital, or one of the doctors at your in-network hospital happens to be out-of-network, or you collapse in the street and an ambulance takes you to an out-of-network emergency room, that $3500 yearly limit suddenly becomes $12500. The insurance company's summary even says: "be aware your network provider might use an out-of network provider for some services (such as lab work). Check with your provider before you get services." And it is very much your responsibility to check these things. So including maximum out-of-network costs, you're now potentially paying $29000 in a year for taxes and healthcare.
And if you have a family? All of these prices increase again. If you live in a county in Florida where that cheapest platinum plan isn't offered? Pay more. If your insurance company suddenly decides that a hospital is unfairly charging too much money for something and refuses to pay? You're now responsible. Remember, this is the country where a surprise air ambulance bill
might be over half a million dollars because the helicopters are owned by independent for-profit companies, not charities like in the UK. There are hidden charges everywhere, and insurance companies do whatever they can to get out of paying for them.
It's worth nothing that many Americans will have health insurance plans with much worse coverage than this one. They'll pay lower monthly premiums, but have significantly higher out-of-pocket costs. The "silver" plan from the same list linked above has a somewhat lower monthly cost but an in-network out-of-pocket annual limit of $7900, for example.