I f I am a USA citizen and on Soc. Sec. and have the monies sent to me to UK, do i still have to pay UK taxes?

Also, can I use my Soc. Sec. Medicare A & B & D medical cards in the UK, if I am a USA citizen?

And how long can I stay in the UK before I have to return to the USA so that I can keep my Soc. Sec. income, etc. Never have been oversea before. Any other advise that you can give would be helpful.

Others have correctly covered the issue on the taxes so I won't step on their toes.

Your Medicare coverage is NOT valid for any medical treatment outside of the US with very limited exceptions for emergency care provided in Canada or Mexico. Medicare coverage is not valid outside the US and its possessions, i.e. Puerto Rico, The US Virgin Islands, Guam, etc. I'd suggest you see if it is possible to sign on for the National Health in the UK. If you have been granted permanent residency status or if you are married to a British Subject you may be eligible for National Heath coverage.

If you have been issued a National Health card with a National Insurance number on it, just sign on at the local Doctor's Surgery. If you don't have an NI number you'll need to check with HM Revenue & Customs or the local NI office to see if you are eligible and if so, apply for a number.

You'll have to ask at the Home Office about the length of your stay. If you only received a passport stamp, your stay is limited to 6 months and you do NOT qualify for the NHS. Report It

I don't think so, as long as you not working and the money sent as a gift (from your parent etc).
I did that when I was on college, and when time to tax return, I had asked my CPA.
About the medicare, I really don't know, but I think if you working in UK, I think you'll get their national health system too.

There is a double taxation agreement between the US and the UK which means that you pay tax in the UK on income received in the UK and you will not be taxed in the US but this is a complex area and depends on your residency status. It also needs to be agreed with the US tax authorities (see the IR website www.hmrc.gov.uk which is very comprehensive gives details of tax rates and thresholds etc)
You cannot use Soc Sec, Medicare etc cards in the UK but you will be entitled to free medical care under the NHS as a foreign resident.

Generally, a US citizen is taxed on worldwide income. If your only income is SS benefits, you won't be required to file in the US. If you have other income, you may need to.

The US/UK tax treaty article 17 states that social security benefits will only be taxed by the country that your are a resident of. So the question becomes are you living in the UK long enough each year to be considered a resident?