So since I've actually gone and booked myself into one of these things, I have gone and made the effort of coming up with an outline training programme. I am doing something somewhat controversial in not actually doing any 'cycling' training per se in it (lol). It is exclusively rowing (ergometer) and weights.
The thinking behind this is:
*One of my biggest problems is being too fat. Lifting weights in a structured programme has worked for me in losing fat very effectively before.
*Rowing machines give very good and precise data feedback
*I believe being strong will make me faster and just as crucially, more resistant to wearing-down and injury. The onus on my training is having the stamina to go the difference, not go toe-to-toe with the local choppers on the Hoggenberg.
*It's something I can really stick to and track results from. I also know how to do it quite comfortably.
*I believe doing lots of cycling puts me at risk of injury from putting all the 'aggro' on my knees and ankles. By contrast I can row for hours and hours and hours without problems, and I am of the view it is highly complementary to making one a good 'all rounder'. There is no 'bike fit' equivalent with rowing, you just put your feet on the machine in the right place and plug away.
*I will be riding the bike every day to work and back, and at weekends I'll be doing actual long rides, audaxes, etc.
It's not a long event (or even technically race), it's about 900 km, but it should give some good feedback on whether this is a working system or not.