Urgent: Can't log in - trying to force update & DB errors

Update: Ryan from https://www.madebykingfisher.co.uk was absolutely fantastic and resolved this for me.

I tried to log in to the backend of my site and was taken to https://domain.com/core/update/ and hit with a number of database errors.

I really don't know what to do—how do I get things working again?

All the errors are along the lines of:

Base table or view not found: 1146 Table '[dbname].perch3_user_privileges' doesn't exist

Clicking "accept these errors and continue" doesn't seem to do anything and just goes around in a loop.

Thank you for anyone that can help—I really need to sort this!

As this is almost entire based on a "perch3_user_privileges" table which doesn't seem to be in my database for whatever reason, could somebody please share the definitions of this table with me? Which columns and values should it have? I'd really appreciate any help.

Update: Ryan from https://www.madebykingfisher.co.uk was absolutely fantastic and resolved this for me.