Please be aware that London has multiple airports and that these results are only for London Gatwick Airport.
From London it is on average the cheapest to fly to Istanbul and to Dubai. (Average prices, based on 77 datapoints.)
Analyse prices for Kota Kinabalu
Analyse prices for Makassar
Analyse prices for Johor Bahru
Analyse prices for Batam
Analyse prices for Kathmandu
Analyse prices for Pekanbaru
Analyse prices for Kuala Lumpur
Analyse prices for Ahmedabad
Analyse prices for Berau
Analyse prices for Guangzhou
Analyse prices for Hanoi
Analyse prices for Kuching