On what I feel like doing. Might take a week, might take a 2 or 3 days.
I know a dirtly little secret about Baldur's Gate. It is possible to get back into Candle Keep before you reach the City of Baldur's Gate... All you need is a rare book of great importance... But I will not say what or where you can find a such an item.
The plot fast forwards when you do this, you get arrested for murder and get to face the Catacombs. It is possible to finish the game, but, it makes things a lot harder as the game starts breaking down. It makes working in Baldur's Gate much harder too, as the moment you enter the city folks start hunting you, making the game extra spicy. The fight at the top of the Iron Throne building becomes BRUTAL, as you face both the seven original foes, plus that insane mage lady you were meant to meet later all at once. Solo, this is fiendishly hard, as she summons those Ogres, and, all of the others start pounding you into pudding. The Sewers become the best way to travel, if you know them well enough.