Tier 2 to Tier 4 dependent visa

Hi
I am studying my post graduation in United Kingdom. I am planning to extend my student visa by doing an other masters since i got scholarship. My husband is here(United Kingdom) in tier 2 visa through an umbrella company. He is so much interested to work in contract than doing fixed term jobs and there are also few issues with the umbrella company. So I just want some guidance to know about Tier 4 dependent visa. Is it possible for him to change from tier 2 to tier 4 dependent visa? Are there any possibilities to apply it from United Kingdom itself? Can I submit the student visa and dependent visa application together when I apply for my visa? If there are any possibilities then could you please guide me with the formalities and procedures to apply for the tier 4 dependent visa..
Thanks.