I made it!
4 days, 340 miles by my Aldi cyclecomputer, 298 on googlemaps, it doesn't know I got over detoured a couple of times though.
Biggest surprise was not the physical demands, I was expecting that. Doing Shap summit on Thursday with the temps in the high 20's was hard, likewise taking the Lancaster canal down to Preston, most of which is untracked was hard.
The worst part was the third morning after leaving Gretna and getting a bit lost, not sure I was going in the right direction or how far I had to go, all the time the temperature rising. That was really hard on the morale. I had a routecard, but they only work if you stick to it and don't stray at all. Couldn't get a signal on the phone so satnav was out as well. Cycle towards the sun (south-ish) until you meet someone! Decided I don't like routecards, next time I'll have a map.
Weighed in when I got home, 23kg of stuff, that's without food and water. 3 water bottles is not enough, I had bottles bungeed to the back, drinking 6+ litres a day and still not peeing a lot! Could probably have done with more.
Bike was a star, held all that up perfectly, the fat tyres really helped my hands, still a touch of numbness in one hand though. My jury rigged rack mounts, petrol hose clips, worked fine. Slow over the bumpy stuff is common sense, anything can break.
Google may say "Don't be evil" but it has a wicked sense of humour! Taking me over the West Pennine Moor to finish my journey with a total of 10,000 foot of climb at an average of 9.3mph.
Will I do it again, damn right!