Please be aware that Istanbul and London has multiple airports and that these results are for all airports serving the city.
The best month to fly between Istanbul and London is April and the most expensive month to fly is September. (Average prices, based on 399 datapoints.)
The cheapest airline flying from Istanbul to London is Pegasus Airlines. They are 60% cheaper than British Airways. (Average prices, based on 407 datapoints.)
The best time to fly is at around 17. (Average prices, based on 429 datapoints.)