What happens to non EU spouse after separation?

[SAA]

Hi all!

I am writing on behalf of a friend of mine (she came from Chine). She came in the UK as a student in April 2005. She got her spousal visa in September 2007.
She and her husband (British) have a year old baby boy. Recently she told me she wanted to separate from her husband because her marriage is not working out.
She is not working but is looking after the baby so she can not afford a normal lawyer.
So the questions are:
1. What papers she needs to prepare for her separation
2. What visa status she has now taking into account her separation
3. Can she get a visa to access to her British child without going back to her country (her spouse visa is exparing in September 2009)
4. When to inform the HO that her marriage has broken down (is it straight after her legal separation or after getting an order for the child?)

5. How will the HO cancel her current visa ? will ask for the passport or it will be automatically while she will be applying for a visa to access to the child??

Please help anybody,
She is really desperete now.

P.S. no domestic violence has been committed there