Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Langkawi to London Heathrow Airport as you normally would.
For a flight from Langkawi to London Heathrow, you will be flying from Langkawi. Langkawi (LGK) is just 7.7 km from the centre of the city. Langkawi is the only Langkawi airport and it handles 0 outbound flights to London Heathrow per day. 1 airline has flights to London Heathrow from Langkawi on a regular basis.
When booking a flight from Langkawi to London Heathrow Airport, you may want to consider flying on Emirates, Etihad Airways or Malaysia Airlines as they are the most popular for this route.