I found this page (dated 23rd April 2021) on freemovement.org.uk that describes the options for people subject to immigration control who are stuck overseas:
https://www.freemovement.org.uk/coronavirus/
Its a lengthy page and I only glanced over it and so I may have missed something, but it appears that unfortunately, as you left the UK after 17th March 2020, you would have to start from scratch with applying for a new entry-clearance visa assuming that you are still overseas by the time your current visa expires, unless your reason for leaving the UK was due to certain "exceptional reasons" (which it would appear you don't qualify for). Certain NHS workers, or a family member of such a worker, can get a free 1 year extension to their current visa due to the Covid situation, so if this applies to you or your partner, make sure you check this out. I encourage you to read through that page that I found. Best of luck!