I've got a self-contained one off DnD 3rd edition campaign that I could throw up and DM in one of the tabletop simulators if anyone was interested. Made it years ago to play with my IRL friends but it never happened since we had other campaigns going at the time and then life got in the way, but I kept hold of it all. 

Don't have pre-made characters so you can be whatever you want in the standard forgotten realms setting, make a new level 1 character and you'll be good to go. I'd expect it to take about 3 hours but depending on how retarded everyone is it could be more or less.