You can buy a FlyWithCE 300 Flight Recorder for £90 including VAT and postage that will record your GPS position every 3 seconds. You can then use one of several tools to see where you went in relation to controlled airspace (I use SeeYou but there are others).
File created is in IGC format.
iPhone/iPad tool APP if you have GPS on your device is WinPilot - does similar.