So at the end I got myself a ticket to SIN for Easter with CX for 497€. All flights are in booking class L, should earn 28066 AY+ points, so not too bad
(HEL-LHR-HKG-SIN-HKG-LHR-HEL)
And CX was kind enough to allow OWS travellers to pick seats w/ extra legroom for free which should make the long Y flights somewhat more bearable.