Turbo Trainer Advice

But you don't want to be doing 2 hours on teh tubro.

You want to be doing an hour of intervals max really. So 2x20.
Unless you have good mental composure and can do an hour of solid pain. But it's not really worth it.

I'd not bother with worrying about real life. Just do what you can do, for a time that you want to do it. And that be that. So 2x20min efforts at a fair hard but not all out effort.

I'm thinking. Something like

50:15, 70+rpm - 15mins
50:21, 70+rpm - 5mins
50:15, 70+rpm - 15mins

I like the idea of getting used to the effort. On the day it will allow me to gauge my starting effort.