I would add that you might want to see if the Hilton has any offer. Of course it's more expensive than the pods but it's a great hotel with proper quiet room. I've seen prices as low as EUR150 but if you leave it late it can be EUR300-400 as well, which I don't think it's worth it. If you have status with Hilton (diamond, gold) then you can have a free breakfast which I think is better than the Finnair lounge offering for Silver or Business passengers. Gold would be a different matter...
Also don't forget if you just buy the BA CE ticket return it should have same day change possibility (check it when you book it) so on the way back you can try to change it to the 8:00am Finnair A350 which has flat beds. As you would arrive on the BA798 quite late you can stay up an another 30-40 min then midnight kicks in and if there is availability you most likely can change it. Don't try at the airport as they are clueless. If you can't do it with the App or web site, just call BA and they should do it. In that way you can get an another 2 hours of sleeping and you should arrive earlier than BA795. (by schedule)