Here's a question. How strange is it to drive on the right side of the road instead of the left for you UK'ers?
surprisingly not that weird, same as driving LHD cars here, it takes some getting used to but is definitely do-able until you need to overtake on a single carriageway
Heathrow is at 98% capacity. Gatwick is quite busy too. Luton and Stanstead are.. meh. Southend isn't very busy, and it depends on what you consider as busy with London City Airport.
Luton is awful and bland, Stansted has spartan facilities, London City Airport is ridiculously expensive and for snobs, Gatwick is closer to Brighton than to London itself and Heathrow is too big. Trains are even worse.
London Ashford Airport has only one commercial airline, LyddAir, who have 5 business class planes and only fly to and from London Ashford and Côte d'Opale Airport in France.