Here's my two pennorthworth
Dover to Calais................if you book online return fares are around £39 with P&O.
Then head down to the Verdun area. Plenty of 1st World War cemetarys and battlefields to visit. You can still pick up old ammo in the fields around Verdun. For a place to stay in the area you can't beat this place
http://www.bikersbedsfrance.co.uk/ Notice the low cost of staying here. Around £30 per night for two people, breakfast included.
Ian and Carol are a great couple, both Bikers, and she's an SV rider herself.
Great roads to ride in that area, not a huge haul from Calais, and well worth a visit.