I think you might like the Mackinaw, or this, or this. They're all designed large to accommodate layering and should provide a load of warmth on their own. Though when I think of a work jacket, even if it's office work, I think of something like this one from Dickies but I have no idea if it's BIFL quality.

You could also use heavy weight thermal underwear and shirts. It'll add substantial heat retention. Wool base layers are good too, I have some Smartwool stuff I like, but that's more useful for being active and managing sweat, so I'll wear heavier cheaper stuff if I'm sitting a lot.

I also recommend the Smartwool Hike Light Cushion Crew Socks, though you might want thicker ones. Darn Tough and Icebreaker are also good for socks. Just wash and dry all that stuff on the lowest settings.

Fingerless gloves could work too even using a computer, though it's not a great match. I like Upstate Stock gloves for their variety.

A black silk scarf wouldn't be out of place either.