How to download torrents from the office?

I would install µTorrent on my home computer and set up the WebUI.

If you have Dropbox, you could use it to remotely start BitTorrent downloads. Basically what you do is set up your BitTorrent client at home to automatically start downloads when .torrent files are added to a folder inside your Dropbox, and then you add .torrent files to that folder from your office via the Dropbox web UI and they'll automatically start on the other side.

If your office has blocked torrent activity, there has to be a good reason.
It is usually not just about bandwidth utilization.

Meanwhile, if you have a home machine active while you are at work, you can control it to work torrents.
This leaves the office network disconnect with the torrent traffic itself.
It becomes entirely your responsibility.