If you earn below 5715 per year you only pay class 2 NI contributions, which is 2.4 pounds per week.
[edit] I forgot to mention that you can apply to be exempted from class 2 NI altogether. I didn't do that because 2.4 pounds per week seemed already very low to me.
My understanding is that income tax as well as NIC contributions go towards funding the NHS. Anyone is eligible for NHS treatment, even foreigners, so it seems inaccurate to say that your contribution to the NIC is what pays for your health care.
I didn't say that and I really don't know how much of the NHS is being paid for by NI contributions.
The point is that in the UK you pay according to your actual profit wheras in other european countries you pay a lot starting on the day you register your business.
Do you have a reference for the "standing charge" in the UK? I've never heard of it.