Originally Posted by
corporate-wage-slave
Terminals C and E are now connected airside, so if you are HBO and with a boarding pass then you can walk to the next building along, C, enter security there and walk all the way around to the E gates. The BA lounge is right on the end of this pretty long walk. You can do it landside too, C merges into E eventually.
If you have to go to the E check-in area then the most direct route is via the central car parks, it is signposted but you need a good sense of direction. There is also a bus transfer between terminals too.
It's easier and a bit shorter to do it landside - B to C is connected upstairs on the departure level, and C to E is at the ground level with arrivals (going through the parking garage is only really useful for A to E). Walking is about 10-15 minutes total time; the bus will be a bit faster but you might have to wait a few minutes for it.
You can enter security at C, however, there are airport staff at the start of the line that check your boarding pass to see if you are flying the right airline (mostly JetBlue for terminal C). They are kind of pointless though as you can tell them that you are flying with a 'JetBlue partner' they just shrug and let you through, as I once did with a JAL boarding pass.