thanks for all the advices..
I want to be at about 2 am cause I want to make a little nap before 8 a.m
departure (is it safe to sleep at the airport in the night?)

I`m arrivine at 8 pm and never having been earlier in London I`m thinking of
some
night sightseeing tour how shoul I arrange it? what should I see to get
the most of
that trip? I would be thankfull for all new advices.
cya in London (in about a week