Travelling out of UK and back before Student Tier 4 visa expires

I am in the UK on a Tier 4 student Visa

I have been offered a place in a workshop in NY that meets every 2 months.  I have to be there in person to participate in the workshop--I can't Skype in. 

Would it be permissible under terms of my Visa to fly to NYC and backto London in Oct and Dec?  Or would I be denied re-entry?

I am in the UK on a Tier 4 student Visa

I have been offered a place in a workshop in NY that meets every 2 months.  I have to be there in person to participate in the workshop--I can't Skype in.  

Would it be permissible under terms of my Visa to fly to NYC and backto London in Oct and Dec?  Or would I be denied re-entry?

When does your Tier 4 visa expire?
When does your course finish at the UK university?
Would you be missing from your UK university course when you attend the workshop in NY every 2 months; or is the NY workshop part of your UK degree?

It expires in january, my course requirements are finished in oct.  the workshop is not part of my degree

There are quite a few posts on immigrationboards.com where they have not been allowed back into the UK on the tier 4 visa as their course had finished. You might want to have a read of some of their posts on that board? Some have said that they did manage to be let back into the UK.

Many students on that site have asked the same as you and the general answer seems to be that if you want to play safe and be in the UK until the end of your tier 4 visa, then don't leave the UK after your course has finished.  

Thank you, I will have a read on those boards as suggested.