To find cheap flights, you can try the following tips:

• Be flexible with your travel dates and times.
• Use flight comparison websites to compare prices from various airlines.
• Sign up for fare alerts from airlines or travel agencies to get notified of price drops.
• Consider flying during off-peak seasons.
• Look for indirect flights or layovers, as they can sometimes be cheaper.
• Book your tickets well in advance to secure lower prices.

The availability of cheap flights can vary, but some airlines that often offer competitive prices on flights from the UK to Pakistan include:

• Pakistan International Airlines (PIA)
• British Airways
• Turkish Airlines
• Emirates
• Qatar Airways
• Etihad Airways

As of my last update in September 2021, there were no budget airlines operating direct flights between the UK and Pakistan. However, some airlines like PIA or other Middle Eastern carriers might offer more affordable options.

Generally, booking your flights several months in advance will give you a better chance of finding cheaper fares. It's a good idea to start looking for flights at least 2-3 months before your desired travel date.

The main airports in Pakistan that receive international flights from the UK are:

• Jinnah International Airport (KHI) in Karachi
• Allama Iqbal International Airport (LHE) in Lahore
• Islamabad International Airport (ISB) in Islamabad
• Benazir Bhutto International Airport (ISB) in Islamabad (Note: Some flights might still operate from the older airport, which was renamed to Islamabad International Airport)

The duration of flights from the UK to Pakistan can vary depending on the departure city and the destination in Pakistan. Generally, direct flights take around 7-8 hours, while flights with layovers can take anywhere from 10 to 20 hours or more.

Travel restrictions and entry requirements can change based on the COVID-19 situation, and it's crucial to check the latest information from official sources before planning your trip. Make sure to check the website of the Pakistan High Commission in the UK or the UK Foreign, Commonwealth & Development Office (FCDO) for up-to-date travel advisories and entry requirements. Additionally, check the airline's website for any specific guidelines they might have for passengers traveling to Pakistan.