I'd echo the pristine tarmac comments - you really don't need any bike upgrades for a comfortable ride. Gearing: I was on 42:16 I think - 1 up from my normal ride. That seemed about right for me - perhaps gear up slightly from what you are comfortable with on an everyday basis as you'll be sitting in groups for most of the course. It really isn't hilly - 1500m of climbing on a 300km ride is flat by most standards. I reckon 10 - 12 hours in the saddle for a comfortable spin round. As above, it does get cold at 4am. I always stayed in the local gyms/schools which they open up for the weekend. About £15 for a couple of night's inside, but as said there are loads of other options.
I'd echo the pristine tarmac comments - you really don't need any bike upgrades for a comfortable ride. Gearing: I was on 42:16 I think - 1 up from my normal ride. That seemed about right for me - perhaps gear up slightly from what you are comfortable with on an everyday basis as you'll be sitting in groups for most of the course. It really isn't hilly - 1500m of climbing on a 300km ride is flat by most standards. I reckon 10 - 12 hours in the saddle for a comfortable spin round. As above, it does get cold at 4am. I always stayed in the local gyms/schools which they open up for the weekend. About £15 for a couple of night's inside, but as said there are loads of other options.