I was a little confused and did a few calculations, only to realise you are indeed out of luck - HEL-LHR (or pretty much anywhere in Britain) gets you just ~50 miles short of the 1.2k miles you need for zone 3. Ahh.

That being said... CX in Y on Southeast Asia - HKG - Northeast Asia (esp PEK/ICN/HND) seems to be a really good steal for OWS... if you ever need an alternative routing to Japan especially. I mean, considering the detour you already have to do to avoid Russian airspace, why not break it up at somewhere which isn't Doha?