I've put my kknnnobbblies on [IRC Mythos 1.95"], but I reckon anything with a bit of tread and at minimum pressure will be ok. All that camping gear should give a bit of traction! I have used Conti Top Touring [old tread pattern, 1.75"] with no problem in soft conditions, just the occasional slight wheelspin. But proper off-road rubber is better, [and a pain on the road.]
I would have thought we would be at Holme-next-the-Sea before dark, with just a few road miles to the campsite. I'm not sure whether to bring my bar-bag too, but its more to do with whether I can stand it rattling. I'll probably experiment with an extra bungee between it and the front rack. As you say Oaky, its essential to have access to the Marmite sarnies.
I'm still heading up to boab's on Friday, so will see you all on Saturday, whether at the Ixworth cafe or subsequently.