Just so you guys know, the visa is issued on the day they receive your passport copies. So please don't make the same mistake as I did and send a passport that is about to expire. Even though I updated them with the new passport, the visa was still the one issued for the earlier passport. So right now I don't have many days.
So this is how it goes:
1) You send the PP copies to London
2) They issue the visa based on that PP. If you update your passport, THEY STILL USE THE OLDER VISA BUT A NEWER STICKER WITH THE NEW PASSPORT #
3) Once they get the sticker in Islamabad, they ask you to send the PP
Just in case it's helpful to anyone.