I too am in a similar position but I think I have worked away around the issues!
I am hitting my mid-century this year and wanted to do something challenging and memorable. I last did any serious cycling 18 months ago when I cycled from London to Paris and then lost a lot of motivation to ride due to work and family pressures. Having got these back under control LEJOG beckoned.
Domestically:-
1) I found a cause that appealed to my wife - in the case the MS Society - a good friend of ours was diagnosed with this disease 15 months ago;
2) I agreed to limit my training to 3 times a week;
3) We both agreed that as I was hitting Hawaii (work it out) this was the time
4) There were two possible sets of dates and I chose the set that best suited family commitments
Work
I am also getting support from work - only moral support really!
1) Tell everyone what you are doing and why;
2) My Facethiong link appears on the bottom of my work emails;
3) So when I'm not around or answering email/phone calls everyone knows I am training
4) And I'm using Facething to keep everyone informed
On the training front the question was then how.
I was very comfortable on London to Paris - even the longest day (110 miles in 30c), despite my longest training ride being around 50 miles. I had also done a five day charity ride a good few years ago and handled that fine too so the day after day eat-ride-eat-sleep-repeat routine was fine. But 12 days of circa 100 miles day? So:-
1) I found a book :- http://www.amazon.co.uk/The-Time-Starve ... B00BBADT1A ,read it and planned accordingly;
2) Current plans are for two short weekly rides and one long ride;
3) This last ride will get longer and longer;
4) The other two will become more intense - faster, pushing hills more etc…
5) I am running a 4 week training cycle: base-build-peak-drop back;
6) I have then a higher level plan that sets out the maximum distance ride I hit in a month;
7) Currently looking at hitting 100 miles in June and then doing 3x100 mile back to back days in July -
In summary:-
Communication is key
Have a plan, share it and stick to it as best you can
Get everyone to buy in to supporting you!
Good luck!