Ride it like two 25s!! Unless you intend to rip the road up with a 1:45, don't worry about a decent warm up, take it slower for the first few miles then gradually increase the pace. You'll be flying by the end.
We'll have to differ on the bottle. Things have changed now, in my day no one took a bottle on a fifty. I would accept that we did not drink enough back then, but I now think the pendulum has swung the other way to a ridiculous degree with riders scared to go further than round the block without a gallon of liquid stored all over the bike.
Unless it is very hot I don't see how you need to drink on a two hour ride.
FWIW, a cage with a bottle therein is supposed to produce less drag than an empty bottle cage as the air flows around the bottle. In that case, unless you are going to remove the cage you may as well take a bottle with a little liquid.
I heard that bottle thing somewhere too (where?). Anyway, one of my many TT rituals, which may or may not be beneficial, and I'm never going to find out- let's face it, is to always ride 10s and 25s with an empty bottle in the cage. Longer ones I'll have a drink.
Yes, I've heard that a bottle increases aero too. I'm definately taking it with me, I can manage a 25 without a drink but I need something come the end of it.
The course on Sunday is 2 laps of a 25 that I've done twice before and there are a few draggy bits to look out but so as long as I don't blow up on them I should manage to get home. Time wise, well 26mph will see me in for 1hr55 but I think that's just wishfull thinking. I'll be delighted to get under 2 hrs.