I did it with 3 mates last June/July. We also did our own route (about 12 percent off road, avoided A-roads as much as poss, 55,000+ ft of total ascent and 1070 miles.
I used a Genesis Croix de fer with Ortlieb Panniers.
Rack – get a disc specific one, I got a – MPart Ridge Pannier Rack – For Disc Brakes, alarmingly bolts rattled loose after about 600 miles, perhaps get better bolts or frequently check them/take spares. I’d suggest getting a Topeak MTX disc rack simply cos Vin Cox used one of these riding around the world, it is a tad heavier than the other options mind. Check there’s nothing remotely sharp in contact with your panniers, my rack rubbed holes in the panniers.
Don’t get a TorTec Ultralite Rear Rack, despite what people say these don’t work well with discs.
Tyres Tubes – All 4 of us didn’t get punctures, we used slick 32mm Continental Gatorskins, even off road these were fine, you can give them a right beating.
I only took one spare tube.
Gears – With set up you have with 10 speed I’d get a 12-36 cassette, a wide range really helps the knees epsecially with loads on the hills.
By a long chain that’ll take powerlinks such as a KMC or Sram one. Once chain is fitted, keep the spare bit you don’t need (hence why buying a long one is good) Buy an additional powerlink and bring that with the spare bit with you. Don’t bother taking another whole chain, if it breaks you only need a few links and the powerlink.
Bike gear I took – chain tool, allen keys, spoke key for adjusting, v. small cloth for cleaning between brake pads, small bottle of chain lube, little philips screw driver, couple of patches and tube glue, small amount of electrical tape.
ALso took a cheap lock and one of the the Kryptonite flex cables.
Don’t forget to factor in weight and space for food and drink, there were days in Scotland and Northumberland where we had to take 3 litres of drink and a lot of snacks.
Also, don’t forget the saddle cream, Chapeau is good and savlon etc!