I can't get to the furnace room as a wolf, Leber keeps killing me. I'm following the GB walkthrough.

A lot of people have trouble with this part. Have you looked at a video walkthrough yet?

I haven't looked at video walkthroughs, it can't be watched and play the game on laptop, at the same time.

You should be able to pause or background your game and then open up a browser to look at a video. Depends on the game, but usually a press of the Windows key or Alt/Tab does it.