Personally, I'd book the F seats and take my chances. If you are lucky you'll get a nicer seat and a private cabin that should trump UD (even with CW food and service).

If you are unlucky you'd get a club seat anyway, albeit possibly in the dorm middle pair but the gamble would be worth the risk for me.

YMMV.

Are you someone that prefers the risk over a certainty or the other way around? Or put another way; what would bother you most? Being in a good UD club seat but knowing you could have had an F seat in hindsight or being in a middle pair lower deck seat because they didn't fill the club cabin (but knowing that you would have been in F had they done so)

Good to hear you found availability and hope you enjoy your flight and trip in any case. Don't forget you don't have to choose the same strategy for both legs.

If I was less risk prone I would choose F out and CW back, even in middle seats on day trip you would have a decent trip and be guaranteed to have CW UD on way back for night flight (so decent sleep in small cabin) and have played the gamble without too much risk. @:-)