For a while I was registered with BUPA when my wife worked, and she was taxed on this as a benefit. I claimed on it twice, and adding up the cost of both operations against what I could have put aside from my self employment over the past 23 years comes to under £4 a week.
You won't get a price on the BUPA website because they want to send a rep to upgrade you, but good old Tesco would charge me £700 a year inc 5% discount for paying a year's premiums up front with a £100 excess. Now just think what I could do with that imaginary £500 a year difference if I'd been putting it away!
I'm ahead of the game, it might work the other way for you

PS
BUPA - British United Provident Association - is a non-profit insurance company