Start date of new leave to remain

[fereshtehizadi]

Hi,
I am a research associate in UCL; My current job is under initial UK visa (leave to entre) expired in 29/03/2019. My Tier 2 (general) leave to remain visa application for Southampton university has been successful; However, neither I have recieved my new BRP card nor signed conttract with Southampton university and I have not resigned from my current job in UCL yet. My start date with new employer is December 3th but I am not able to start without BRP card. Please help me in this hard situation with my questions;

Could I still come to my office in UCL when I am still waiting for my BRP card (without salary)?

Could I still extend my current visa with my current employer (UCL)?

Thanks a lot in advance for any help

[CR001]

Useful to state what date your new visa was approved

Could I still extend my current visa with my current employer (UCL)?

Your visa for your previous sponsor would have been cancelled when your new tier 2 visa was issued, so no you cannot extend your visa with UCL. You would have to apply for a new visa and pay all the fees again.