Just to update. I made it to Leipzig. Did 501km for my festive 500, then hopped a train for the rest. I did it on my GP 4 seasons in the end, but carried the Top Contact winters, just in case. Never needed them. I did have some grip issues comedy off roading near the end, the rear was all over the place. Also has a puncture on the rear, 30km from the end, a flint went through. Quick tube swap, and onwards.
Thanks everyone for the help and advice.
J