It sounds as if you guys are not severely limited regarding the number of days you can allocate for a LEJOG, in which case I would say to you "Go for it", and stop looking for someone to do it with and generally making excuses.
Without time constraints, there is no need to set targets, just cycle as far as you feel like very day. Doing it off peak, accommodation will be easy to find with the aid of local tourist information offices, so no need to book in advance which merely introduces stress. If you have a mechanical you could be under pressure to reach a pre booked location. You don't even need to tell anyone of your plans, then if you get tired at say Carlisle and go home, your friends will still be impressed when you inform them you have cycled the length of Scotland or England. Draw an imaginary line on the map from LE to Bristol, and look for the closest side roads to that line, and that is your route, repeat between Bristol and Carlisle and that's half your route planning done already. You can always get advice on this forum for fine tuning of your chosen route, so start plotting now.......
http://www.getamap.ordnancesurveyleisure.co.uk/
I find the most difficult part of any multi day tour, is getting beyond my own front door.
