It's all up in the Air right now and the open skies only comes in next year March 2008 , And it's no secret that BA want to move it's operations from LGW to LHR .
Thats why most people don't mind taking the pay cut if it means getting into LHR . Also remember your only perm after 6 Months so they can do what they want .
I'm sure you will be fine !! but don't go in with blinker's on .
Good luck with your start date