Generally on all courses the dog picks the sheep up from the set out and fetches them through the fetch panels (which are in a direct line from the set out to the handler's post), so if the dog is fetching correctly directly to the handler, the sheep should go through the panels. The only exception to this would be if the course had a dog-leg fetch, but you generally wouldn't find that in the novice class. Sometimes the fetch is so short that fetch panels aren't practical, and I've set sheep for the novice class where the sheep are held right at or just behind the fetch panels, so obviously the panels don't really play a role in such cases.
If the sheep miss the panels on the fetch, you lose points. You aren't allowed to go back and try to get it right (what's done is done). On the drive, it's a matter of perspective, but if the sheep don't break the plane created by the panels, the handler can get the dog to move them back over (if they're off line) and try to make the panels, but in all cases, once the sheep have passed the plane (think of it like a line drawn through the panels and out to each side), then you just lose points and keep on to the next obstacle.
As for the pen, here in this part of the country, the novice-novice class usually includes a wear, which is when the handler walks along with the sheep following and the dog keeping the sheep to the handler (in the northeast, an assisted drive is allowed, in which the handler would walk with or behind the dog while the dog drives the sheep). In that case, the handler would "lead" the sheep to the pen. In the upper classes, the handler must stay at the post until all phases of work up to the pen are completed. So the sheep have to make or miss the last drive panel before the handler can leave the post and head to the pen. In the case in the open class where the shed occurs before the pen, then the handler generally has to stay at the post until the sheep enter the shedding ring. After shedding the handler has the dog regather the sheep in the shedding ring and then bring them to the pen. That would be the only other scenario where the handler would be walking ahead of the sheep to the pen.
Again, much depends on what part of the country you're in as to what to expect on the novice-novice course. I've seen courses where the handler sends the dog from the pen, the dog fetches to the handler at the pen, and then the sheep are penned, but I think in most cases the class would include some sort of short wear/drive after the fetch and before going to the pen.