About my Tier1 extension, due next year.

[hsyasin]

Hi all,
I want expert opinion on this, the thing is, i've a full time job plus i work for another company as a part time over the weekends.
The query is about that part time work, the way i work and get paid is, i submit them an excel file with my hours that i've worked in a month and then they pay me straight into my account without tax. Now, i can submit the tax returns myself, but i really need to know that, do i really need an accountant or can i do all the returns myself and submit that at the end of the year and just attach my NI contributions and the hours sheet for each month for my extension?

keeping in mind, this part time work is helping me get the minimum salary points that i need for my extension.