Leaving the UK for a non eu country, e.g. switzerland /latin america, what happens to all tax and NI

Dear all,
I was wondering if anyone has gone through this and can help. I am planning to leave the Uk for good. Having lived here for almost 15 years, I was wondering what would happen to all the tax and National Insurance that I have paid so far ? I know that you can credit all the monies towards you pension/ healthcare, when moving to an EU country.

What happens when you are moving somewhere like switzerland or the americas. Do i get the NI credited in anyway, so I can claim a pension when I retire, and will i get any tax back?

Also, on the financial side of things: can you continue to pay your credit cards when living abroad via bank transfer or do I need to pay it all off before i leave.

To some of you these might be quite naive questions, but since I have just starting toying with the idea, I would be really grateful for any input.

Kind regards,

Ana Clara