Originally Posted by
thinkingallowed
Oh well, if they don't let me then I'll take them to Schiphol and check them in there.
Obviously you would need to leave enough time to collect and recheck your bags so a back-to-back is out of the question. Alternatively if you have a longer gap at LHR before the long haul flight you could leave them at the luggage store or in your car.
If you do try to check in for the LH before flying to AMS only show your KUL boarding pass and don't mention AMS.