Manston doesn't have much of a catchment area for passengers. To the North and East is nothing apart from North Sea. To the West are the Medway towns, but by the time you get to Rochester, it's just as easy to head along the M25/M11 to Stansted where there is more choice. To the South and South West are the likes of Canterbury, Dover etc, but again heading any much further West Gatwick becomes a better option.
Also I think the nearest ATM machine is in Ramsgate town centre!