Garuda Indonesia is currently offering an excellent business class fare to Bangkok via Jakarta. Unlike many of the deals we feature, this involves departing from Heathrow and not positioning yourself in Europe.
The cheapest price seems to be on the Garuda website. You are looking for days showing £630 outbound and £450 inbound. I cannot replicate the fare via ITA Matrix so I can’t access the fare rules regarding booking dates, but the deal is there – try 15 March out, 26 March back for example.
My review of Garuda business class is here albeit that is based on a short hop between London and Amsterdam back in the days when they stopped off on the way.
Garuda is a member of SkyTeam so you can credit your flight to Flying Blue, Delta or one of the other SkyTeam programmes if you don’t want to earn miles with Garuda.
Your best option to maximise your miles when paying is American Express Preferred Rewards Gold. This offers double points – 2 per £1 – when you when you book flight tickets directly with an airline. Our review of Amex Gold is here.