Most UK insurers offer Three months EU cover as standard - but check to make sure, always keep the following documents with you: drivers licence, insurance doc, MOT and V05 (vehicle registration).
Check Germanys driving regs, they are bastads for pulling over UK plated cars and can generally find something to nail you on, such as not having a fire extinguisher or not having matching tyres on the same axle, high visibility vest, and hazard sign. I think its also compulsary to have a first aid kit in the vehicle.
Its illegal to run out of fuel on the German Autobhans.
Check this out:
France - breathalysers for all and reflective jackets for motorcyclists
Several changes have been made to motoring laws in France in support of the International Decade on Road Safety.
From the 1st July 2012 all drivers in France, including vehicles registered outside of France, must carry one unused breathalyser, to French certification. This includes motorcycles.
From the 1st November 2012, failing to produce a breathalyser will result in an on-the-spot fine.
theaa.com/motoring_advice/overseas/compulsory_equipment.html
Theres a list of EU regulations.