About sponsor ship

[Jagat]

Hello ,
I have got tier 4 visa which is valid upto April 2016. I have taken ACCA in which I cannot show progress due to that the college has already informed to UkVi. And I am waiting for the letter.
Luckily I have got another tier 2 sponsor who is ready to help me in sponsoring me because of my previous work experiences but I have no work except work placement in my current visa.
Now my question is that can I work with the employer until he issue me COS. furthermore he want to give me training as well. Can my current visa effect him and create problem for him and me.
Secondly if UkVi send my 60 days letter that won't effect me in switching to tier 2.
I am in great confusion what to do ? Immediate response will be highly appreciated. Shall I take help of the solicitor in my case? If yes can you please recommend one for me.
Thank you for giving time in reading it.