I've never seen flights sub £300 to Pakistan - Islamabad so this is just a heads up. If you go via Skyscanner flights show up for £300 with Shaheen Airlines for various dates in May. Proceed From Skyscanner to book but may sure you pay in Pakistan Rupees PAK and it converts to under £300. I have friends heading to Pakistan for a wedding in May and they paid significantly more for flights. 32k of hold luggage included and 7kg hand luggage.