Its such a good feeling when you realise that all the hard work is paying off,i started cycling to lose a few pounds and now i cant think of much else,wanting to plan a good long ride like yours for next year for our honeymoon,what sort of bike did you use?
there were several people doing it on MTBs, mostly hardtails. Personally I think it would be like doing it on a tractor. You definitely don't need suspension, the tracks can be muddy in places but not that bad (depending on the weather). I think 35mm tyres are enough and give a little comfort for the length of ride. Puncture protection is a must especially around Southport, Liverpool and Hull.
I like the Kaffenback because it's simple, light, tough and flexible. Personally I wouldn't use SPDs because of the risk of slipping but that's just me.
One recommendation would be around navigation. Mostly the signage is good, but it can get confusing where a sign goes missing (near Aintree) or where the path splits (walkers one way, cyclists another). If you can do so, recce the route. Have the maps handy (they are very good).
Personally I'm a self-confessed gadget freak who will find any excuse to use one.

I got an excellent waterproof case for my Samsung SGS2 and followed the planned routes using ViewRanger. Battery life is an issue. I carried an external battery and kept the phone charged by USB (unplugging when it rained). Worked well for me, but the paper maps are excellent and certainly up to the job. I just like the GPS to tell me exactly where I am. :controlfreak: