Originally Posted by
stut
Spanish shopping-mall-with-airbridge operators BAA are indeed very keen for you to turn up early and spend lots of money, sorry, time at the terminal, but in reality, there's no need. Two is plenty - I usually leave much less than this.
I believe the bolded fix is what the newspapers would prefer you to say, stut
Outside of the shopping area (and I've heard lounges, but I've not yet made it inside the SkyTeam lounge, that comes on Friday for the first time for me), T4 is a pretty drab place to hang out. Since OP has no status, optimizing time at LHR (minimizing but not to the point of cutting it close) seems like a good plan. The gates DL uses, even if at the end of the corridor, are not all that far from security, fortunately.