I'm flying out tomorrow too, but on BA109. Have been in the front row of Premium before on the DXB-LHR route (21B), extra legroom was nice, wasn't too bothered about the arm rests. Also nice not disturbing anyone when you want to get up and stretch your legs. Row 21 didn't have a misaligned window on my flight.

http://www.thebasource.com/seatmaps.html might be worth checking out. Assuming you're not gold, the front row (if not already reserved by golds / paid seat selections) would be available at T-24.