Still working part time but also working on personal business - benefits change?

m33r4

I work 4 days a week part making a total of 23.5 hours weekly.
I have 3 children all in full time education and under my care.
My husband works full time.
The HMRC is aware of the above and I get working tax credit (although next year this will be stopped from Apr 2012) + child tax credit. I don't get any other benefits.

I am currently in the process of setting up my own web-based shop on which I work about 7 hours in the week. I have not yet launched this shop so there is no revenue. However, I do "work" extra hours on this and eventually this will hopefully bring in some revenue once I launch it live on the net.

My questions:

1. In the meantime, before even opening shop, since I am "working", be it unpaid, inform the HMRC that I am doing extra hours per week?
2. Once I do launch, should I inform the HMRC that I have this other job I spend this much time on?
3. Will either of the above affect my working tax or child tax credit?

Thanks.

nannytone_2

you should inform HMRC if only to register your business.