Equally - it will depend on time of day as I think you can only use your freedom pass after 9:30am - so off-peak only.
Freedom Passes are valid on London Overground services before 0930 weekdays, so will open the gates at FH at all times.
I noticed London Overground have put a 'helpful' map outside the ticket office showing the long winded diversion route for pedestrians who can't use the footbridge without a travelcard/freedom pass.