It depends how they do it & if u have booked reserved seating - at Wembley the lower tier of the stands was unreserved seating, hence if u had a general admission ticket - u could sit there - or get a wristband for the pit - U could basically go anywhere apart from the upper tiers, which were reserved. Hence if it is a reserved seat - u won't be allowed to go in the pit / general standing (Not legally anyway).

Mike