Thank you very much! I will be at LHR T5 so I assume there is a gallery lounge. I also have Amex and priory pass as a backup.
I tried Finn site and selected seats awhile back. Funny though, maybe because of the flight time change, I now have two PNRs on BA.com with 1 letter difference. Same flight, same seats but one with BA flight number but no e ticket number and another with Finn codeshare and e ticket number ...