Applying for working tax credit (self employed) questions, help please!

Hi everyone,
I'm registered self employed and I turnt 25 in June.
I am single, no children and live with my Mother and her husband.

I can apply for working tax credit, correct?

I have some questions regarding the application:
1. When it says working hours must be 30 or more per week. Mine are but a different kind. For example: I am a make-up artist, model and web-designer. I spend each week differently. Every day I spend time on the computer doing some sort of work be it promoting myself, web-design, editing. Or out doing make-up or modeling. Does this still class as 30 or more hours a week? Some days I'm on a shoot working for 12 hours in 1 day! But, like I said: It's varied each week so do I just put 30 hours?

2. My Mum is disabled and as I mentioned, I still live at home. Will this affect my application at all?

Thanks