I'm flying MAN-LHR-LAS-LHR(-MAN) next week (departing next week, returning the following week) in WTP for a work trip. I'll obviously be travelling HBO and given that it turns out I need to be in London that evening anyway, my plan is to drop the last LHR-MAN leg (which isn't til 5hrs later anyway). However, the thought of people sitting on a plane that could get away early whilst waiting for me to not board weighs slightly on my conscience! Whenever I have done an ex-EU previously I have always honoured the last leg.

So I have 2 questions:

1) Will it even matter? I assume if I have not repassed security by the cut off time anyway, then they will not be waiting for me when boarding?

2) It's very easy to not check in if using the app, but from memory, I can't recall being able to use a mobile boarding pass at LAS - is this still the case? In my experience, a check in assistant will always be very keen to check you in for all the flights they can on your itinerary. What other options would work? Printed PDF boarding pass? Use the machines?