Do the AMS-LHR the night before, and either route BKK-HKG overnight, then LHR-AMS on the evening back-to-back, or BKK-LHR-AMS during the day with a night in AMS, and it's easy. Certainly, it's more jetlag friendly than QR in my experience.

I also like routing through HKG as you get into BKK in the evening so you have a very short, well rested day even if you hit the nightlife when you land.