~Confused~ Do I setup a Limited Company or an Umbrella Company???

Ok, so I'm currently working for Contractor A, who has me assigned to work to Contractor B, who have me working on a big project for SuperGlobalSoftwareCompany (SGSC). After I told all of the above that I was moving to Scotland, the SGSC manager I was supporting asked me to continue working remotely for them.

So Contractor B has set up an exchange with a staffing agency in the UK so that I would be paid in GBP into my UK current account. A person from the UK agency contacted me today with some details of the contract, and she mentioned that I need to confirm and let them know if I have my own Limited Company or wish to use an Umbrella Company? I have no idea what this means? What are the tax implications of either of these? Does that mean I am technically self-employed? Here, I am paid by Contractor A, who takes out all relevant taxes and I am employed by them (not self-employed).

If I am considered self-employed, doesn't that really screw up my US taxes?

Please help!

ETA: If it helps, the agency in Britain that has contacted me is Networkers International PLC

If you set up a limited company you are self-employed. You have to handle your own taxes. As someone who has a limited company, you'll need an accountant, there's no way around it.

If you go through an umbrella company, you can be classed as self-employed or as an employee of the umbrella company, depending on the umbrella company. The benefit of paying an umbrella company is that they'll handle the UK tax side of things and that makes it much easier -- this is what my DH does, as he's a dual national, and it just makes filing the US taxes much simpler.

If you set up a limited company you are self-employed. You have to handle your own taxes. As someone who has a limited company, you'll need an accountant, there's no way around it.

If you set up a limited company, you are an employee of the company you created. But yes, you need an account for the annual stuff.

Running a limited company:
https://www.gov.uk/running-a-limited-company

Being self-employed is a different kettle of fish and should not be confused with running a limited company.

Self-employed:
http://www.hmrc.gov.uk/selfemployed/register-selfemp.htm
http://www.hmrc.gov.uk/selfemployed/