Yep I think they are from Luton, interestingly though most over here are mainly Ryanair rather than other airlines.
Haven't seen an A380 over here yet, possible I've missed them but like you say departing they go further south and arriving they come in further north over Chelmsford way.
The Qantas and Cathay pacific were probably Heathrow, BA one though I just checked the flight tracker ad it said
Stansted.
Hadn't thought about getting one, may well do one day though as that kinda thing interests me lol also like to get a radio receiver.
At the moment just using a few phone apps,
A bit empty compared to daytime lol because Heathrow runway is closed for a few hours this time of night.
Really dead around 2-3am barely anything up there.