Proposed route Nottingham UK - Darmstadt, Germany. Looking for any thoughts/advice if you know any of the areas

http://bikeroutetoaster.com/Course.aspx?course=175545

I will pass through London in the way shown on the map to visit family and have a bed to sleep on so no need to warn me off!!

And help or advice would be appreciated as I plot routes according to the map and then see what happens on the road...I will be on a vintage peugout which does not like climbing.

Happy cycling to all :o)