Hi,
First of all you are not from the land of the pub...you are going to it!
Assuming you are looking for real ales I would recommend the following, in no particular order, apart from bracketing them in terms of locality:
Near Town Hall:
City Arms
The Circus Tavern (Portland Street). Don't take the cat...no room to swing it.
Almost next door, The Old Grey Horse
Near Briton's Protection is The Peveril of the Peak (bright green tiles outside). Over the road is Rain Bar.
Others of note are the Marble Arch (on the way out of the city on Rochdale Road. Jolly Angler and Crown and Kettle..both near Norther Quarter.
Where are you staying? Best runs from in town are along the canal...run towards Old Trafford.
Enjoy, and let us know what you get up to!