Thought you might find this app helpful. Saved me the other day on an SEP revalidation where I had to plan a navex at zero notice (not just a GH sortie as I had wrongly anticipated). CAA Examiner said to me when I arrived at airfield, "nip next door and plan your navex, your route is..."
Anyway, after a frazzled 10 mins with dynosauric whizz wheel (borrowed from local flying club) a quick trip to the toilets with my mobile phone, I was able to check my hand-calculated nav and wind corrections via a detailed PLOG sent by email.
Click here (
flylogical: Flight nav planning by email ) for more info (this is a non-commercial, free resource, hope you find it useful)