The CTC website is pretty good for route planning, so I believe. Or maybe Audax UK. The windy mostly blows from South to North, apparently so most people go Lands End - John O' Groats, not the other way around.
I went north to south for logistical reasons (my wife was prepared to meet me at Land's End which resulted in a lift home). I have heard that the wind is supposed to make this the tougher approach but I don't know it makes that big a difference, I seem to recall the wind was about 50-50 on my trip.
.... and we are No 176 in the Ultimate Links site - AND our map stuff is available for a modest donation to Macmillan Cancer Support (so far we have "sold" about 60 copies ... so someone must like it!!)
The CTC has an entire forum devoted to LeJog, but the best way to plan a route is to get a road atlas to decide your daily routes and then plot using google earth, mapsource or tracklogs if you are downloading onto a GPS.