Ediburgh Uber

On my last day in Edinburgh I need Uber to take me to an airport bus station at 7am, which is only a short distance (10 mins may be). Because time is critical I prefer to book a car in advance. I am not in UK yet and I tried to use Uber app to book a car, it asks me to try on-demand ride or different pick-up point. Does it mean it doesn't accept advance booking? If so, is it secure to call on-demand ride at such early morning? If no car responds on that morning then I'll be in trouble.