The F level attendant is very particular about checking if you are allowed to be there. She has a clipboard with a list of name of HON/F pax for that day and looks you up. When I got an op-up to F and moved a level up, she got all worked up because I wasn't on the list, took my my BP and called the front desk to check. So do make sure the front desk is OK with it
(Mainly because DO&Co will charge OS or LH for the services rendered)