Having travelled across Canada and down to Texas heading for Argentina, I would say that detailed planning is a waste of time. Just plan the route roughly by country and places you want to see so you can check out the paperwork you need to cross the borders.
Secondly, nearly everything electronic has failed, from my wind up torch to my high end camera, so take equipment you can toss in the bin without worrying about the cost of replacing it locally. Low tech stuff lasts better.
You can test out your equipment by going for weekend camping trips, the weather in UK is mild compared to most places so even a winter weekend will prepare you for a cold nights camping somewhere. Can you light your stove in high winds, is your sleeping bag warm enough, what's it like putting up your tent in the rain? Better to find out before you leave. I have broken 4 tent pole sections so far, luckily Wal-Mart sell them over here.
Last week I camped near Silver City, Arizona; at about 6000ft it was about 80F during the day, but below 40F at night when the cold air flowed down the mountain. I woke up cold at 2am until I put a fleece over my shirt and put my jeans on. (Jeans are not recommended as they take to long to dry.)
That's another thing, how long will it take your clothes to dry when you wash them in a motel room sink, or get soaked in a rainstorm? Yep, I have a full Hein Gerick storm suit, but it just takes too long to get out and get into. It's easier to travel on regardless, in my everyday fabric m/c suit, and dry out later; no doubt I will change my opinion when I reach a tropical rain storm
These stupid day to day domestic things become more important than 'Day 54 - Take Hwy 19 south to Xville' - that stuff you can make up as you go along.
Me? I'm loving it.