Pika!!! You're so ready!!
Yes the aid stations should have fluids for you but be careful in the handoff zones, it's a prime place to have a crash. Good on you for getting your nutrition and hydration down, that's really tough when the weather changes so drmatically like that.
I had the same problem you are having with my polar HRM. I haven't had it with the Garmin but I would suspect that it might be a transciever battery issue.
I can't wait to hear how you do!!
Living life like there's no tomorrow.
http://gorgebikefitter.com/
2007 Look Dura Ace
2010 Custom Tonic cross with discs, SRAM
2012 Moots YBB 2 x 10 Shimano XTR
2014 Soma B-Side SS