Originally Posted by BA6501

You've counted one security checks too many:
- enter the terminal, security check for all baggage. You can use either the right or left areas, with the left ("East") one being marginally closer to BA's check-in, desks 35-38. This time of year, and considering the 8am departure, I'd allow 10 minutes for this security checkpoint.
- passport control, make sure you have filled out your pink departure card (received at check-in) - I'd allow 10-15 minutes here.
- the lounges are straight ahead, up the escalator (on your right) or stairs (on your left, again marginally closer). Turn right at the top and go to the LAT lounge, or left and go to the Cedar Lounge if you have a Priority Pass
- they'll call the flight in the LAT lounge with sufficient time, I normally go no more than 5 minutes after they've called the flight as the queues at the next security checkpoint are unpredictable (you can tell by looking at the flight info screens and looking for flights departing from gates 1-12, though). Allow 5 minutes for this checkpoint, luckily ME201 (BEY-LHR, similar time, always from the same wing) is an A320 tomorrow rather than an A330.
- turn right and head to gate 12, just one minute away, and hopefully by then the queue for BA's security will have shortened quite a bit. They certainly won't leave without you at this stage!