UK Visa advice for changing "from Full time to Part time PhD"


I am in 4th year PhD and writing my thesis now. I have a once in a lifetime offer from a very reputed organisation outside UK. It is a dream job for my skills. I don't have a formal offer yet.... But would want to understand the subsequent issues.

I know it will be a challenge to move into part-time and then submit+ defend the thesis.... But I am up for it.
Has anyone experienced this... Please share your advice and tips!!!!

I believe to persuade my supervisor and the university to get approval (Hope I will.....).

What will be the visa status once I move into Part-time? Tier-4 is only for fulltime studies. I think it will be Student Visitor visa?

Can anyone of you share your views on this PLEASE!!!
Thank you in advance!