Hi Katy,
Looking in the system, yes this flight is via Singapore and you would be due to land in Siem Reap at 09:50hrs.
For your return journey, it looks like you leave Danang 16:20hrs and arrive Heathrow at 05:55hrs. The return flight is flying via Siem Reap and Singapore.
As you mention above - these are provisional times and all flights are subject to change and would be confirmed in final documents.
Kindest regards,
Julia