Omie is right.
We've just crossed from the Iranian border at Taftan and are currently in Lahore.
I posted more information on another thread that there is really only 1 Northern route open to non-Pakistani people.
The roads are poor, potholes are huge, often roads are single lane with a 2ft drop either side. Oncoming buses never give way, trucks sometimes do.
You will have an security escort half-way across the country, use it!
We only saw the devastating effects of the flooding in 1 town were tents were errected along the whole of road side.
Fuel is available everywhere... so is food & water, we imagined the worst, but all shops appear fully stocked.
Pakistani people are wonderful, they are kind and helpful.
Let me know if you have any questions and I will do my best to answer them when I can get internet access.