Where in Pakistan can I buy a kettle BBQ?
You can buy it online. Here's a decent one. Here are cheaper ones from the same site. Here's another site with some smaller options.

When we discussed this in chat you told me that you'll be staying with your uncle. The advantage of buying it online is that you can have it shipped to your uncle's address so that it's there even before you arrive. You'll be all ready to fire up the corncobs on the very first day.

Amazon India has the hands down best selection, and if they don't ship to Pakistan you can use this service to get it delivered. But do be wary of potential customs fees and extended delivery time if you go this route.

You might have to ask your uncle to use one of his payment cards (in case some of these vendors don't accept foreign cards.)