Thanks for the replies. So I contact Finnair on Chat through the App and “As I can see it, you don’t have a business light ticket so lounge access is included.” Which I screengrabbed and sounds positive although later in the chat they did say because BA purchased the ticket they couldn’t quite tell.

I might pop to Haneda this morning to try and work it all out. There’s no option to buy lounge access on the app or anything so I guess that might also mean it’s included. Oh well, guess it’ll all become clear later!