One easy thing you can do for yourself is to do is to plot your route on a half-mil paper map before setting off - and look carefully at what's underneath the flight path. (And check the NOTAMs, of course!)
I've frequently seen light aircraft overfly active airfields at a dangerous height, i.e. below the height indicated on the half-mil maps. For one example, see airprox report 05207 in <http://www.airproxboard.org.uk/docs/423/ukabbk18.pdf>
I suspect that the relevant airfields are not shown on some (all?) electronic moving maps.