TAX CODE/Self employment while still full employed/PAYA TAX CODE problem

bskol

So I registered as a self employed since August and I was also full time employed. From tax 1060l, after registration i had a tax code changed to 619T(on PAYA). I found on the internet that T stands for Temporary and that i should wait till they will give me correct tax code. I thought that I would have to do self-assessment and that my tax code would not change at all. Since that time I had change my full time employer and now with the new employer I'm on yet different tax code - 440L W1. So after they been cutting a large piece of my salary every month i thought its time to call tax office (i would rather do it thru online form). So here is my question, what should i tell them ? how should i write it down on that online form? what to include and what can they ask me? Since i started that self employment i earn 0£ on it, just expenses. I would rather do self-assessment then have my wage cut and then refunded after a year.
Please help!:|