Hmm, just say there were 13 based aircraft, does the airport have enough check-in desks for those with luggage?
Also factor in extra road traffic particularly for the first wave when there is no public transport. I have first hand experience when the tipping point is reached and everything grinds to a halt. All seems fine then suddenly nothing moves.
Does SEN have the luxury of a long approach road to keep any queues away from local road? How big is the drop off zone? Would Southend remain the UK’s favourite airport? If it could then it would be doing very well.