Can i contribute fully to our SEP and a roth ira in the same year?

The SEP is funded by the employer. Assuming you are self-employed, as long as you have a Net Profit on Schedule C in excess of 1/2 your self-employment tax, you can make a SEP contribution as an employer.

Further assuming that you are ineligible for making a deductable traditional IRA contribution (income limits apply when you are an active participant in an employer sponsored plan such as the SEP), a ROTH IRA contribution is allowable subject to Adjusted Gross Income limits of $95,000 to $110,000 for single taxpayers and AGI between $150,000 and $160,000 for married filing a joint return.

So in answer to your question, "contribute fully" would depend on the facts and circumstances of what your AGI is.