All that said directly above by homebrewk^
Why no milk before? If you're wondering; milk would curdle in your stomach from all the activity and you'll end up puking it out.

Keep a steady pace and stay hydrated. Do not hesitate to take advantage of any support crew, resources, and handouts if needed.

In addition you might want to tweek your gear ratio because the uphill portions sounds long and grueling on a fixed gear.