Here's a common question on contributing to your self-employed plan and an IRA.  We went to the irs.gov site for an answer.

Can a person make a contribution to a SEP-IRA and a Roth IRA, too?

Yes, you can make a contribution to a SEP-IRA and a Roth IRA. See Chapter 2 of Publication 590, Individual Retirement Arrangements (IRAs), for the requirements to contribute to a SEP and a Roth IRA. However, your SEP IRA contribution and Roth IRA contribution can not be made to the same IRA.