I’m a fair way into the game and decided to add the unofficial patches because I wanted the additional content.

The game worked, just a tad sluggish, however when I returned to Tarant via the World Map, only half of the bridge loads up and the other half stays black. The clock in the corner continually whirs and I can see the newspaper boy talking but I can't move. I tried the config setting changes to no avail. I tried to walk in from the side and when I hit that part of the bridge it goes blurring like an acid trip.

I deleted and reinstalled the base game - still same problems.

Any ideas? Do I need to even go back to Tarant? Plot wise I’m supposed to be in Ashbury.

EDIT:SOLVED

Thanks for the input Kerebron.

I decided to redownload the unofficial patch, clicked some different install settings, downloaded the hi res patch and voila, the other half of Tarant showed back up.

If you have a savegame made in the unpatched version of the game, you can't use it in the patched version, obviously. You could (and should) expect all kind of weird behaviour if you mix those two, as the number of fixes/changes in UAP is huge.
You have to start a new game.